Light alkane dehydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention discloses a low-carbon alkane dehydrogenation catalyst as well as a preparation method and application thereof, and the low-carbon alkane dehydrogenation catalyst comprises an active component and a carrier, wherein the active component comprises one or more of oxides of In, W, Ce, Pr, Nd and Ti; the carrier is a composite carrier containing zinc magnesium aluminate spinel, ZrO2 and SiO2; the low-carbon alkane dehydrogenation catalyst provided by the invention has better strength, more excellent carbon deposition resistance and more stable catalytic performance.

Description

Technical Field

[0001] This invention belongs to the field of catalysts, specifically low-carbon alkane dehydrogenation catalysts, their preparation methods, and applications. Background Technology

[0002] Low-carbon olefins such as propylene and isobutylene are important basic raw materials in the petrochemical industry, used to produce basic materials such as plastics and rubber, and play a key role in fine chemicals and pharmaceuticals. With the rapid depletion of fossil fuels, traditional low-carbon olefin production methods, such as catalytic cracking and naphtha steam cracking, can no longer meet the growing demand. Compared to traditional production routes, low-carbon alkane dehydrogenation technologies (such as propane dehydrogenation PDH and isobutane dehydrogenation IDH) have become an important process in industrialized olefin production due to their advantages such as high olefin yield, strong profitability, reduced carbon emissions, and improved energy efficiency.

[0003] The dehydrogenation of low-carbon alkanes is a strongly endothermic reaction in which the conversion rate is limited by thermodynamic equilibrium, and the selection of a suitable catalyst is crucial to this technology. Currently, the most widely used alkane dehydrogenation technologies are UOP's Oleflex process and Lummus's Catofin process, which employ moving bed reactors and fixed bed reactors, respectively. In addition, the fixed bed PDH process of Linde, BASF, and Statoil, the fixed bed Star process of ThyssenKrupp, the fluidized bed FBD process of Snamprogetti and Yarsintz, and the fluidized bed catalytic dehydrogenation process of Dow are also mature and industrially applied low-carbon alkane dehydrogenation technologies.

[0004] Industrially mature dehydrogenation catalysts for low-carbon alkanes are mainly supported Pt-based and Cr-based catalysts, with Al₂O₃ as the support. Pt is a precious metal, and its high price leads to high catalyst costs. Pt-based catalysts are prone to sintering at high temperatures, causing irreversible deactivation. Furthermore, Pt is highly sensitive to impurities in the feedstock, requiring pretreatment before use. While Cr is inexpensive, the hexavalent Cr in the catalyst is highly toxic, posing a threat to human health and the environment. In addition, both types of catalysts are prone to coking, leading to deactivation. Therefore, there is an urgent need to develop novel, highly stable, and environmentally friendly catalysts that combine resource and environmental advantages.

[0005] Compared to platinum and chromium oxides, Ga, V, Mo, Ce, In, Zn, W, Pr, and other metals are relatively abundant. Their oxides possess suitable CH bond selective activation capabilities and low dehydrogenation energy barriers, making them promising alternative systems for dehydrogenation catalysts. However, these catalysts generally suffer from inherently low activity, and it is also necessary to avoid activity reduction caused by reduction and reconstruction or over-oxidation of oxide catalysts. Based on this, patent application CN102451677A discloses an alkane dehydrogenation catalyst comprising four components: component A is an oxide of one or more of Ti, Nb, Ta, Mo, W, Re, In, or Ga; component B is one or more of MgO, P2O5, ZrO2, Al2O3, or SiO2; component C is an oxide of one or more of Zn, Cd, and Sn; and component D is a mixture of one or more alkali metal oxides or alkaline earth metal oxides. The resulting catalyst exhibits high activity, high selectivity, good stability, and high mechanical strength. However, this method introduces alkali metals or alkaline earth metals to adjust the acidity or alkalinity of the catalyst. The introduction of such promoters can cover the active sites to some extent, which can have a negative impact on the reaction.

[0006] Patent application CN116059991A discloses a low-carbon alkane dehydrogenation catalyst with zinc oxide as the active component. The catalyst composition includes 20%-50% zinc oxide, 20%-65% a first promoter component comprising a zirconium dioxide-silica composite oxide and at least one first metal element (titanium, manganese, tin, tungsten), 0.1%-10% a second promoter component comprising at least one second metal element (lithium, sodium, potassium, magnesium, barium, calcium), and 10%-50% a binder. One major problem with this approach is that the high ZnO content leads to ZnO reduction under dehydrogenation conditions, resulting in Zn loss and affecting catalyst lifespan. Another problem is the low catalyst activity, primarily manifested in low catalytic conversion.

[0007] Compared to fixed-bed and moving-bed processes, fluidized-bed propane dehydrogenation has higher gas-solid contact efficiency, better heat and mass transfer performance, and greater advantages in reaction efficiency, operational flexibility, and adaptability to complex operating conditions. However, the catalyst is violently disturbed in the high-temperature circulating fluidized bed, resulting in severe wear between particles and requiring frequent replenishment of fresh catalyst. This catalyst wear and loss hinders the widespread adoption of the circulating fluidized-bed process. Summary of the Invention

[0008] 1. Problem to be solved and objective of the invention

[0009] To address the issues of wear and poor stability in existing low-carbon alkane dehydrogenation catalysts, this invention provides a low-carbon alkane dehydrogenation catalyst; furthermore, this invention provides a method for preparing the low-carbon alkane dehydrogenation catalyst; and the application of the catalyst in the dehydrogenation reaction of low-carbon alkanes (preferably propane and isobutane) to olefins.

[0010] 2. Technical Solution

[0011] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0012] The first aspect of the present invention provides a low-carbon alkane dehydrogenation catalyst, said catalyst comprising an active component and a support;

[0013] The active components include one or more of the following: oxides of In (indium), oxides of W (tungsten), oxides of Ce (cerium), oxides of Pr (praseodymium), oxides of Nd (neodymium), and oxides of Ti (titanium).

[0014] The carrier is a composite carrier containing zinc magnesium aluminate spinel, ZrO2, and SiO2.

[0015] As a preferred embodiment of any of the first aspects of the present invention, the zinc magnesium aluminate spinel has the general formula Zn. x Mg y Al2O4, where: x+y=1, x≠0, y≠0, x≥y.

[0016] As a preferred embodiment of any of the first aspects of the present invention, the mass ratio of zinc magnesium aluminate spinel, ZrO2, and SiO2 is (50-98):(1-30):(1-20).

[0017] As a preferred embodiment of any of the first aspects of the present invention, the mass ratio of zinc magnesium aluminate spinel, ZrO2, and SiO2 is (75-93):(5-15):(2-10).

[0018] As a preferred embodiment of any of the first aspects of the present invention, the content of the active component is 1-40 wt%, and the content of the carrier is 60-99 wt%, calculated as the total mass of the active component and the carrier.

[0019] As a preferred embodiment of any of the first aspects of the present invention, the content of the active component is 2-15 wt%, and the content of the carrier is 85-98 wt%, calculated as the total mass of the active component and the carrier.

[0020] As a preferred embodiment of any of the first aspects of the present invention, the specific surface area of ​​the carrier is 50-120 m². 2 / g.

[0021] As a preferred embodiment of any aspect of the present invention, the pore volume of the carrier is in the range of 0.15-0.3 cm. 3 / g.

[0022] As a preferred embodiment of any of the first aspects of the present invention, the preparation of the carrier includes the steps of:

[0023] S1. Prepare a solution containing soluble salts of zinc, magnesium, aluminum, and zirconium, a surfactant, and a homogeneous precipitant, and carry out a hydrothermal reaction;

[0024] After the hydrothermal reaction is completed, the product is obtained by filtration and washing.

[0025] S2. Mix the solvent with the hydrothermal product to obtain a slurry; then add a silicon source, binder, and pore expander, and dilute with solvent; subsequently perform spray drying and calcination to obtain a carrier.

[0026] In a preferred embodiment of any of the first aspects of the present invention, in S1, the molar ratio of zinc to magnesium is 1:(0.2-1);

[0027] Based on the total molar amount of zinc and magnesium, the ratio of aluminum to the total molar amount of zinc and magnesium is 1.8-2.5, the preferred ratio is 1.9-2.2, and the optimal ratio is 2-2.1.

[0028] In a preferred embodiment of any of the first aspects of the present invention, in S1, the molar ratio of zinc, magnesium, aluminum, zirconium, surfactant, homogenizing precipitant, and deionized water, based on the total amount, is 1:(0.2-0.5):(1-4):(80-500).

[0029] As a preferred embodiment of any of the first aspects of the present invention, the mass of the zirconium is calculated according to ZrO2 and is denoted as m. Zr ;

[0030] The quality of zinc, magnesium, and aluminum is based on Zn x Mg y Calculate Al₂O₄(x+y=1, x≠0, y≠0, x≥y), and label it as m. ZnMgAl ;

[0031] The mass of silicon is calculated based on SiO2 and denoted as m. Si ;

[0032] The mass of the carrier is according to m Zr m ZnMgAl m Si The sum is calculated and denoted as m. 载体 ;

[0033] The amount of zirconium added is m 载体 1-30 wt%;

[0034] Preferably, the amount of zirconium added is m. 载体 5-15 wt%.

[0035] As a preferred embodiment of any of the first aspects of the present invention, the mass of the zirconium is calculated according to ZrO2 and is denoted as m. Zr ;

[0036] The quality of zinc, magnesium, and aluminum is based on Zn x Mg y Calculate Al₂O₄(x+y=1, x≠0, y≠0, x≥y), and label it as m. ZnMgAl ;

[0037] The mass of silicon is calculated based on SiO2 and denoted as m. Si ;

[0038] The mass of the carrier is according to m Zr m ZnMgAl m Si The sum is calculated and denoted as m. 载体 ;

[0039] The amount of silicon added is m 载体 1-20 wt%;

[0040] Preferably, the amount of silicon added is m. 载体 2-10 wt%.

[0041] As a preferred embodiment of any of the first aspects of the present invention, in S2, the m 载体 The mass ratio of the binder and the pore expander is 1:(0-0.1):(0-0.05).

[0042] Preferably, in S2, the m 载体 The mass ratio of the binder and the pore expander is 1:(0.05-0.1):(0.005-0.05).

[0043] As a preferred embodiment of any of the first aspects of the present invention, in S2, there are no particular requirements or limitations on the amount of solvent added before spray drying. The amount most suitable for spray drying can be added within the range of suitable spray drying instruments / circumstances.

[0044] As a preferred embodiment of any of the first aspects of the present invention, in S2, the conditions for spray drying include:

[0045] The inlet air temperature is 150-500℃;

[0046] The outlet air temperature is 80-200℃.

[0047] As a preferred embodiment of any of the first aspects of the present invention, in S2, the conditions for spray drying further include:

[0048] The atomizer speed is 20-80Hz;

[0049] The feeding speed is 10-80 rpm.

[0050] As a preferred embodiment of any of the first aspects of the present invention, in S2, the conditions for the calcination treatment include: a calcination holding temperature of 500-800°C; preferably a calcination temperature of 550-700°C; and a calcination holding time of 2-8 hours.

[0051] As a preferred embodiment of any of the first aspects of the present invention, in S2, the conditions for the calcination treatment include: the calcination atmosphere being air.

[0052] In a preferred embodiment of any of the first aspects of the present invention, in S1, the zinc-containing soluble salt includes, but is not limited to, inorganic salts of zinc, such as one or more combinations of zinc nitrate, zinc acetate, zinc sulfate, or zinc chloride.

[0053] As a preferred embodiment of any of the first aspects of the present invention, in S1, the soluble salts of magnesium include, but are not limited to, inorganic salts of magnesium, such as one or more combinations of magnesium nitrate, magnesium acetate, magnesium sulfate, or magnesium chloride.

[0054] As a preferred embodiment of any of the first aspects of the present invention, in S1, the soluble salts of aluminum include, but are not limited to, inorganic salts of aluminum, such as one or more combinations of aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0055] As a preferred embodiment of any of the first aspects of the present invention, in S1, the soluble salts of zirconium include, but are not limited to, inorganic salts of zirconium, such as one or more combinations of zirconium oxychloride, zirconium nitrate, zirconium sulfate, zirconium chloride, and zirconium acetate.

[0056] As a preferred embodiment of any of the first aspects of the present invention, in S1, the surfactant includes one or more combinations of cetyltrimethylammonium bromide (CTAB), sodium citrate, cetyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium bromide (DTAB), polyethylene glycol octylphenyl ether (Triton X-100), Tween-20, Tween-80, and oleic acid.

[0057] In a preferred embodiment of any of the first aspects of the present invention, in S1, the homogenizing precipitant includes one or more of urea, hexamethylenetetramine, ammonia (containing >10% ammonia), and ammonium carbonate.

[0058] As a preferred embodiment of any of the first aspects of the present invention, in S2, the silicon source may be selected from SiO2 powder, kaolin, acidic silica sol, alkaline silica sol, sodium silicate, tetraethyl orthosilicate, water glass, preferably one or more combinations of acidic silica sol, alkaline silica sol and tetraethyl orthosilicate.

[0059] In a preferred embodiment of any of the first aspects of the present invention, in S2, the binder includes one or more of guar gum powder, sodium carboxymethyl cellulose, and methyl cellulose.

[0060] As a preferred embodiment of any of the first aspects of the present invention, in S2, the pore-expanding agent includes one or more combinations of polyvinyl alcohol, hexadecyltrimethylammonium bromide, polyethylene glycol, ammonium bicarbonate, and ammonium chloride.

[0061] A second aspect of this invention provides a method for preparing a dehydrogenation catalyst for low-carbon alkane, comprising the steps of:

[0062] S1. Prepare a solution containing soluble salts of zinc, magnesium, aluminum, and zirconium, a surfactant, and a homogeneous precipitant, and carry out a hydrothermal reaction;

[0063] After the hydrothermal reaction is completed, the product is obtained by filtration and washing.

[0064] S2. Mix the solvent with the hydrothermal products to obtain a slurry; then add a silicon source, binder, and pore expander, and dilute with solvent; subsequently, perform spray drying and calcination to obtain a carrier;

[0065] S3. The support is impregnated with a solution containing metal ions; then activated, dried, and calcined to obtain the low-carbon alkane dehydrogenation catalyst.

[0066] The metal ions include one or more of In, W, Ce, Pr, Nd, and Ti.

[0067] It is important to clarify that if the prepared catalyst is desired to exhibit superior wear resistance during use, or to possess better strength properties, three key points must be considered during the preparation process: First, conventional co-precipitation methods should be avoided in step S1. Experiments have shown that products obtained through alkali co-precipitation have large particles, exhibiting unfavorable strength properties and pore structure. Second, as the zirconium source for zirconium oxide formation in the support, adding it simultaneously with the raw material for zinc magnesium aluminate spinel formation in step S1 will result in a product exhibiting more favorable strength properties. Third, as the silicon source for silicon dioxide formation in the support, adding it in step S2 will result in a product exhibiting more favorable strength properties.

[0068] As a preferred embodiment of any of the second aspects of the present invention, in S1, the molar ratio of zinc to magnesium is 1:(0.2-1).

[0069] Based on the total molar amount of zinc and magnesium, the ratio of aluminum to the total molar amount of zinc and magnesium is 1.8-2.5, the preferred ratio is 1.9-2.2, and the optimal ratio is 2-2.1.

[0070] In a preferred embodiment of any of the second aspects of the present invention, in S1, the molar ratio of zinc, magnesium, aluminum, zirconium, and surfactant to homogenizing precipitant and deionized water, based on the total amount, is 1:(0.2-0.5):(1-4):(80-500).

[0071] As a preferred embodiment of any of the second aspects of the present invention, the mass of the zirconium is calculated according to ZrO2 and is denoted as m. Zr ;

[0072] The quality of zinc, magnesium, and aluminum is based on Zn x Mg y Calculate Al₂O₄(x+y=1, x≠0, y≠0, x≥y), and label it as m. ZnMgAl ;

[0073] The mass of silicon is calculated based on SiO2 and denoted as m. Si ;

[0074] The mass of the carrier is according to m Zr m ZnMgAl m Si The sum is calculated and denoted as m. 载体 ;

[0075] The amount of zirconium added is m 载体 1-30 wt%;

[0076] Preferably, the amount of zirconium added is m. 载体5-15 wt%.

[0077] As a preferred embodiment of any of the second aspects of the present invention, the mass of the zirconium is calculated according to ZrO2 and is denoted as m. Zr ;

[0078] The zinc, magnesium, and aluminum are in accordance with Zn x Mg y Calculate Al₂O₄(x+y=1, x≠0, y≠0, x≥y), and label it as m. ZnMgAl ;

[0079] The mass of silicon is calculated based on SiO2 and denoted as m. Si ;

[0080] The mass of the carrier is according to m Zr m ZnMgAl m Si The sum is calculated and denoted as m. 载体 ;

[0081] The amount of silicon added is m 载体 1-20 wt%;

[0082] Preferably, the amount of silicon added is m. 载体 2-10 wt%.

[0083] As a preferred embodiment of any of the second aspects of the present invention, in S2, the m 载体 The mass ratio of the binder and the pore expander is 1:(0-0.1):(0-0.05).

[0084] As a preferred embodiment of any of the second aspects of the present invention, in S1, the conditions for the hydrothermal reaction include:

[0085] The insulation temperature is 80-150℃;

[0086] The heat preservation time is 6-20 hours.

[0087] As a preferred embodiment of any of the second aspects of the present invention, in S2, there are no particular requirements or limitations on the amount of solvent added before spray drying. The amount most suitable for spray drying can be added within the range suitable for the selected spray drying instrument / situation.

[0088] As a preferred embodiment of any of the second aspects of the present invention, in S2, the conditions for spray drying include: an air inlet temperature of 150-500°C;

[0089] The outlet air temperature is 80-200℃.

[0090] As a preferred embodiment of any of the second aspects of the present invention, in S2, the conditions for spray drying further include: the atomizer rotation speed is 20-80Hz;

[0091] The feeding speed is 10-80 rpm.

[0092] As a preferred embodiment of any of the second aspects of the present invention, in S2, the conditions for the calcination treatment include: a calcination holding temperature of 500-800°C; preferably, a calcination temperature of 550-700°C.

[0093] The roasting and heat preservation time is 2-8 hours.

[0094] As a preferred embodiment of any of the second aspects of the present invention, in S2, the conditions for the calcination treatment include: the calcination atmosphere being air.

[0095] As a preferred embodiment of any of the second aspects of the present invention, in S3, the total amount is calculated based on the sum of the mass of the oxide corresponding to the metal and the carrier; the content of the oxide corresponding to the metal is 1-40 wt%, and the content of the carrier is 60-99 wt%.

[0096] As a preferred embodiment of any of the second aspects of the present invention, in S3, the total amount is calculated as the sum of the mass of the oxide corresponding to the metal and the mass of the carrier; the content of the oxide corresponding to the metal is 2-15 wt%, and the content of the carrier is 85-98 wt%.

[0097] As a preferred embodiment of any of the second aspects of the present invention, in S3, the conditions for the impregnation treatment include: an impregnation time of 4-24 hours and an impregnation temperature of 20-40°C.

[0098] As a preferred embodiment of any of the second aspects of the present invention, in S3, the solution containing the active component is brought into contact with the carrier to complete the impregnation. The manner of contact is not particularly limited. For example, the carrier may be immersed in the solution containing the active component, or the solution containing the active component may be brought into contact with the carrier by spraying.

[0099] As a preferred embodiment of any of the second aspects of the present invention, in S3, during impregnation, the volume of the solution containing metal ions is the same as the volume of the carrier, calculated by volume; that is, the equal-volume impregnation method is preferred.

[0100] As a preferred embodiment of any of the second aspects of the present invention, in S3, the activation conditions include: a temperature of 50-90°C and a time of 2-10 hours.

[0101] As a preferred embodiment of any of the second aspects of the present invention, the drying conditions described in S3 include: a temperature of 100°C-160°C and a time of 4-10 hours.

[0102] As a preferred embodiment of any of the second aspects of the present invention, in S3, the conditions for the calcination treatment include: a calcination holding temperature of 500-800°C; preferably a calcination temperature of 550-700°C; and a calcination holding time of 2-8 hours.

[0103] As a preferred embodiment of any of the second aspects of the present invention, in S3, the conditions for the calcination treatment include: the calcination atmosphere being air.

[0104] As a preferred embodiment of any of the second aspects of the present invention, in S1, the zinc-containing soluble salt includes, but is not limited to, inorganic salts of zinc, such as one or more combinations of zinc nitrate, zinc acetate, zinc sulfate, or zinc chloride.

[0105] As a preferred embodiment of any of the second aspects of the present invention, in S1, the soluble salts of magnesium include, but are not limited to, inorganic salts of magnesium, such as one or more combinations of magnesium nitrate, magnesium acetate, magnesium sulfate, or magnesium chloride.

[0106] As a preferred embodiment of any of the second aspects of the present invention, in S1, the soluble salts of aluminum include, but are not limited to, inorganic salts of aluminum, such as one or more combinations of aluminum nitrate, aluminum sulfate, and aluminum chloride.

[0107] As a preferred embodiment of any of the second aspects of the present invention, in S1, the soluble salts of zirconium include, but are not limited to, inorganic salts of zirconium, such as one or more combinations of zirconium oxychloride, zirconium nitrate, zirconium sulfate, zirconium chloride, and zirconium acetate.

[0108] As a preferred embodiment of any of the second aspects of the present invention, in S1, the surfactant includes one or more combinations of cetyltrimethylammonium bromide (CTAB), sodium citrate, cetyltrimethylammonium chloride (CTAC), dodecyltrimethylammonium bromide (DTAB), polyethylene glycol octylphenyl ether (Triton X-100), Tween-20, Tween-80, and oleic acid.

[0109] As a preferred embodiment of any of the second aspects of the present invention, in S1, the homogeneous precipitant includes one or more combinations of urea, hexamethylenetetramine, ammonia water [containing >10% ammonia], and ammonium carbonate.

[0110] As a preferred embodiment of any of the second aspects of the present invention, in S2, the silicon source may be selected from SiO2 powder, kaolin, acidic silica sol, alkaline silica sol, sodium silicate, tetraethyl orthosilicate, water glass, preferably one or more combinations of acidic silica sol, alkaline silica sol and tetraethyl orthosilicate.

[0111] As a preferred embodiment of any of the second aspects of the present invention, in S2, the binder includes one or more of guar gum powder, sodium carboxymethyl cellulose, and methyl cellulose.

[0112] As a preferred embodiment of any of the second aspects of the present invention, in S2, the pore-expanding agent includes one or more combinations of polyvinyl alcohol, hexadecyltrimethylammonium bromide, polyethylene glycol, ammonium bicarbonate, and ammonium chloride.

[0113] In a preferred embodiment of any of the second aspects of the present invention, in S3, the active component includes one or more of the following: oxides of In (indium), W (tungsten), Ce (cerium), Pr (praseodymium), Nd (neodymium), and Ti (titanium). It should be noted that the source of the active component can be a nitrate, acetate, ammonium salt, chloride, or metal oxide of the corresponding element.

[0114] According to any embodiment of the second aspect of the present invention, the low-carbon alkane dehydrogenation catalyst described in any embodiment of the first aspect of the present invention can be prepared.

[0115] The third aspect of the present invention provides the application of the low-carbon alkane dehydrogenation catalyst as described in any embodiment of the first aspect above, or the low-carbon alkane dehydrogenation catalyst prepared by the method provided in any embodiment of the second aspect above, in the reaction of low-carbon alkane dehydrogenation to olefins.

[0116] A fourth aspect of the present invention provides a method for dehydrogenating low-carbon alkanes to olefins, comprising a catalytic dehydrogenation to olefins stage:

[0117] To react pure alkane raw materials in the presence of a catalyst;

[0118] The reaction temperature is 540-640℃;

[0119] The reaction pressure (gauge pressure) is 0-0.1 MPa;

[0120] The mass hourly space velocity (MSV) of the alkane is 0.2-8 h⁻¹. -1 ;

[0121] The catalyst is a low-carbon alkane dehydrogenation catalyst as described in any embodiment of the first aspect of the present invention or a low-carbon alkane dehydrogenation catalyst prepared by the method provided in any embodiment of the second aspect of the present invention.

[0122] According to any embodiment of the fourth aspect of the invention, a catalyst regeneration stage is further included:

[0123] First, the catalyst that needs to be regenerated is purged with an inert gas containing water vapor. The purging temperature is 540-640℃ and the purging time is 10-30 minutes.

[0124] Subsequently, air is introduced for high-temperature calcination, with the holding temperature being 620-670℃ and the holding time being 10-240 minutes.

[0125] According to any embodiment of the fourth aspect of the present invention, the inert gas containing water vapor has an inert gas content of 20-60 wt%.

[0126] In any embodiment of the fourth aspect of the present invention, the inert gas is preferably nitrogen.

[0127] The fifth aspect of this invention provides a method for regenerating a used catalyst (specifically, the used catalyst refers to a low-carbon alkane dehydrogenation catalyst as described in any embodiment of the first aspect of this invention or a low-carbon alkane dehydrogenation catalyst prepared by the method provided in any embodiment of the second aspect of this invention, after undergoing a low-carbon alkane dehydrogenation to olefin reaction), comprising:

[0128] First, the catalyst that needs to be regenerated is purged with an inert gas containing water vapor. The purging temperature is 540-640℃ and the purging time is 10-30 minutes.

[0129] Subsequently, air is introduced for high-temperature calcination, with the holding temperature being 620-670℃ and the holding time being 10-240 minutes.

[0130] According to any embodiment of the fifth aspect of the present invention, the inert gas containing water vapor has an inert gas content of 20-60 wt%.

[0131] In any embodiment of the fifth aspect of the present invention, the inert gas is preferably nitrogen.

[0132] Beneficial effects

[0133] (1) The low-carbon alkane dehydrogenation catalyst provided by this invention uses zinc magnesium aluminate spinel as the core support. Structurally, Mg 2+ Partially replaces Zn in zinc aluminate spinel 2+ It can reduce the surface acidity of the support, giving the support a larger specific surface area, which is beneficial for the dispersion and fixation of active components. It also allows the support to have a large number of oxygen ion vacancies, avoiding the problems of low selectivity and excessive carbon buildup in the dehydrogenation reaction process.

[0134] Meanwhile, the support also contains ZrO2 and SiO2, the introduction of which can effectively enhance the strength and thermal stability of the catalyst. Furthermore, the support has an optimized surface channel structure, resulting in a higher specific surface area, which is beneficial for coke diffusion. Therefore, the synergistic effect of ZrO2 and SiO2 with zinc magnesium aluminate spinel gives the final catalyst support excellent anti-coking performance and catalytic stability.

[0135] The support possesses a large number of oxygen ion vacancy active sites, which inherently exhibit certain dehydrogenation catalytic activity. Furthermore, the active component interacts with the support, effectively regulating the electronic structure and chemical properties of the active component. The active component and ZrO2 in the support exhibit a bimetallic synergistic effect, enhancing CH activation. Simultaneously, electronic interactions exist between the active component, ZrO2, and SiO2, promoting propylene desorption, reducing side reactions, minimizing the production of CH4, C2H6, and other cracking products, and improving olefin selectivity. Moreover, it further promotes the formation of oxygen ion vacancy active sites in zinc magnesium aluminate spinel, facilitating the dehydrogenation reaction, reducing the adsorption of coking precursors, and delaying catalyst deactivation.

[0136] (2) The low-carbon alkane dehydrogenation catalyst provided by the present invention is a composite support containing zinc magnesium aluminate spinel, ZrO2 and SiO2, rather than a physical mixture of zinc magnesium aluminate spinel, ZrO2 and SiO2 after they are prepared separately; the composite support provided by the present invention has better strength, better anti-coking performance and more stable catalytic performance compared with the mixture of the three physical mixtures.

[0137] (3) The preparation method of the low-carbon alkane dehydrogenation catalyst provided by the present invention adopts a homogeneous co-precipitation method without adding alkali in the early stage of the support preparation. The formation and growth of crystal nuclei are relatively uniform, which is conducive to the formation of precipitate particles with narrow particle size distribution and optimizes the surface pore structure of the product.

[0138] Furthermore, by controlling the addition points of zirconium and silicon sources during the preparation process, the resulting product can exhibit more favorable strength properties.

[0139] (4) The low-carbon alkane dehydrogenation catalyst provided by this invention is suitable for fluidized bed dehydrogenation processes to produce olefins from low-carbon alkanes, and can effectively improve heat and mass transfer and fluidization performance: the catalyst contains a multiphase oxide support, which has a better specific surface area and pore volume, reduces bulk density, optimizes the fluidization state during application, is beneficial to heat and mass transfer, reduces structural collapse at high temperatures, and significantly reduces the wear index. The catalyst has good hydrothermal stability and can maintain stable performance during the reaction and regeneration switching process of the fluidized bed device. Attached Figure Description

[0140] Figure 1 XRD diffraction patterns of the zinc magnesium aluminate spinel composite ZrO2 and SiO2 support in Example 1 and the Zn-Mg spinel support in Comparative Example 3;

[0141] Figure 2 The XRD patterns of the catalysts obtained in Comparative Example 1 and Examples 1, 3, and 4 are shown. Detailed Implementation

[0142] This disclosure will be more readily understood by referring to the following description, taken in conjunction with the accompanying drawings and examples, all of which form part of this disclosure. It should be understood that this disclosure is not limited to the specific products, methods, conditions, or parameters described and / or illustrated herein. Furthermore, the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting, unless otherwise stated.

[0143] It should also be understood that, for clarity, certain features of this disclosure may be described herein in the context of individual embodiments, but may also be provided in combination with each other in individual embodiments. That is, unless obviously incompatible or specifically excluded, each individual embodiment is considered to be combinable with any other embodiment, and such combination is considered to represent another different embodiment. Conversely, for brevity, various features of this disclosure described in the context of individual embodiments may also be provided individually or in any sub-combination. Finally, while a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or substructure may also be considered an independent embodiment in itself.

[0144] Unless otherwise stated, it should be understood that each individual element in the list and each combination of individual elements in the list will be interpreted as a different embodiment. For example, a list of embodiments denoted as "A, B, or C" should be interpreted as including embodiments "A", "B", "C", "A or B", "A or C", "B or C", or "A, B, or C".

[0145] In this disclosure, the singular forms of the articles “a,” “one,” and “the” also include the corresponding plural references, and references to a particular value include at least that particular value, unless the context clearly indicates otherwise. Thus, for example, a reference to “substance” is a reference to at least one of such substance and its equivalents.

[0146] When an item is described using the combined terms “...and / or ...", the description should be understood to include any one of the listed items and all combinations thereof.

[0147] Generally, the use of the term "about" indicates an approximation that can vary depending on the desired characteristics obtained from the disclosed subject matter and will be interpreted in a context-dependent manner based on function. Therefore, those skilled in the art will be able to interpret a degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about." In other cases, a gradient within a range of values ​​can be used to determine the range of differences allowed by the term "about." Furthermore, all ranges in this disclosure are inclusive and composable, and references to values ​​described within a range include every value within that range.

[0148] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0149] The present invention will be further illustrated below with reference to specific embodiments, but these embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field. The essential features and significant effects of the present invention can be seen from the following embodiments. The described embodiments are some, but not all, embodiments of the present invention, and therefore do not limit the present invention in any way. Any non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are within the protection scope of the present invention.

[0150] Example 1

[0151] 148.76 g of zinc nitrate hexahydrate, 51.29 g of magnesium nitrate hexahydrate, 525.27 g of aluminum nitrate nonahydrate, and 53.05 g of zirconium oxychloride octahydrate were dissolved in 4076 g of deionized water along with 247.62 g of hexadecyltrimethylammonium bromide (CTAB) and 272.07 g of urea. The solution was stirred until completely dissolved, yielding a clear solution. This solution was placed in a high-pressure reactor and hydrothermally reacted at 120°C for 10 hours. The resulting slurry was washed with five times the volume of deionized water, and then filtered to form a filter cake.

[0152] The washed filter cake was re-pulped with deionized water, and then mixed with 50.05g of acidic silica sol (30% solid content), 7.51g of guar gum powder, and 4.50g of polyvinyl alcohol for 2 hours. After mixing, it was spray-dried with an inlet air temperature of 300℃, an outlet air temperature of 150℃, an atomizer speed of 40Hz, and a feed rate of 40rpm.

[0153] The microspheres obtained by spray drying were calcined at 650°C for 5 hours in air to obtain a zinc magnesium aluminate spinel composite ZrO2 and SiO2 support. The XRD pattern of the support is shown in the figure. Figure 1 As shown.

[0154] 4.93 g of ammonium metatungstate hydrate and 11.58 g of cerium nitrate hexahydrate were dissolved in a certain amount of deionized water to form a solution containing the active components. The amount of water was sufficient to meet the requirement of equal volume impregnation. The carrier was then immersed in the above solution for equal volume impregnation for 10 hours. After that, it was sealed and activated in an oven at 55°C for 5 hours, then dried at 120°C for 4 hours, and finally calcined at 600°C for 4 hours to obtain the low-carbon alkane dehydrogenation catalyst.

[0155] The low-carbon alkane dehydrogenation catalyst prepared in this embodiment is supported by zinc magnesium aluminate spinel Zn. 0.71 Mg 0.29 The composite carrier of Al2O4, ZrO2, and SiO2, calculated based on the total mass of the active component and the carrier, has an active component content of 6 wt% and a carrier content of 94 wt%.

[0156] Example 2

[0157] 89.26 g of zinc nitrate hexahydrate, 56.42 g of magnesium nitrate hexahydrate, 390.20 g of aluminum nitrate nonahydrate, and 70.36 g of zirconium oxychloride octahydrate, along with 156.90 g of sodium citrate and 160.24 g of urea, were dissolved in 4161 g of deionized water and stirred until completely dissolved to obtain a transparent solution. This solution was placed in a high-pressure reactor and hydrothermally reacted at 110°C for 12 hours. The resulting slurry was washed with six times its volume of deionized water, and then filtered to form a filter cake.

[0158] The washed filter cake was re-slurried with deionized water, and then mixed with 106.22g of alkaline silica sol with a solid content of 25% and 6.64g of sodium carboxymethyl cellulose for 1 hour before spray drying. The inlet air temperature of the spray dryer was 350℃, the outlet air temperature was 170℃, the atomizer speed was 35Hz, and the feed rate was 60rpm.

[0159] The microspheres obtained by spray drying were calcined at 650°C for 4 hours in air to obtain a zinc magnesium aluminate spinel composite ZrO2 and SiO2 carrier.

[0160] 19.22 g of indium nitrate hydrate was dissolved in 200 ml of deionized water. The support of the composite oxide was added to the solution with stirring. The mixture was stirred for 30 min and sonicated for 10 min. After that, it was impregnated for 12 hours. Then, it was sealed and activated in a 60 °C oven for 4 hours, then dried at 140 °C with the oven open for 6 hours, and finally calcined at 650 °C for 4 hours to obtain the low-carbon alkane dehydrogenation catalyst.

[0161] The low-carbon alkane dehydrogenation catalyst prepared in this embodiment is supported by zinc magnesium aluminate spinel Zn. 0.58 Mg 0.42 A composite support of Al2O4, ZrO2, and SiO2. Based on the total mass of the active component and the support, the content of the active component is 5 wt%, and the content of the support is 95 wt%.

[0162] Example 3

[0163] 109.76 g of zinc acetate dihydrate, 24.65 g of magnesium sulfate heptahydrate, 450.23 g of aluminum nitrate nonahydrate, and 5.09 g of zirconium nitrate pentahydrate, along with 132.08 g of CTAB and 141.49 g of urea, were dissolved in 5218 g of deionized water and stirred until completely dissolved to obtain a transparent solution. This solution was placed in a reaction vessel and hydrothermally reacted at 100°C for 8 hours. The resulting slurry was washed with seven times the volume of deionized water, and then filtered to form a filter cake.

[0164] The washed filter cake was re-slurryed with deionized water, and 3.49g of acidic silica sol with a solid content of 31% and 2.16g of polyvinyl alcohol were added and mixed for 1.5 hours. The mixture was then spray-dried with an inlet air temperature of 350℃, an outlet air temperature of 170℃, an atomizer speed of 40Hz, and a feed rate of 60rpm.

[0165] The microspheres obtained by spray drying were calcined at 500°C for 4 hours in air to obtain a carrier for zinc magnesium aluminate spinel composite ZrO2 and SiO2.

[0166] 31.29 g of neodymium nitrate hexahydrate was dissolved in a certain amount of deionized water, with the water volume meeting the requirement of equal volume impregnation. The carrier of the composite oxide was added to the above solution and impregnated for 12 hours with equal volume. Then, it was sealed and activated in a 50°C oven for 6 hours, then dried at 140°C for 8 hours, and finally calcined at 680°C for 4 hours to obtain the low-carbon alkane dehydrogenation catalyst.

[0167] The low-carbon alkane dehydrogenation catalyst prepared in this embodiment is supported by zinc magnesium aluminate spinel Zn. 0.83 Mg 0.17 A composite support of Al2O4, ZrO2, and SiO2. The total content of the active component is 10 wt%, and the content of the support is 90 wt%, calculated based on the sum of the masses of the active component and the support.

[0168] Example 4

[0169] 148.76 g of zinc nitrate hexahydrate, 128.23 g of magnesium nitrate hexahydrate, 750.38 g of aluminum nitrate nonahydrate, and 342.59 g of zirconium oxychloride octahydrate were dissolved in 7313 g of deionized water along with 444.27 g of hexadecyltrimethylammonium bromide (CTAB) and 488.13 g of urea. The solution was stirred until completely dissolved, yielding a clear solution. This solution was placed in a high-pressure reactor and hydrothermally reacted at 150°C for 10 hours. The resulting slurry was washed with six times the volume of deionized water, and then filtered to form a filter cake.

[0170] The washed filter cake was re-pulped with deionized water, and then mixed with 215.13g of acidic silica sol with a solid content of 30%, 16.22g of guar gum powder, and 9.73g of polyvinyl alcohol for 2 hours. After mixing, it was spray-dried with an inlet air temperature of 300℃, an outlet air temperature of 150℃, an atomizer speed of 40Hz, and a feed rate of 40rpm.

[0171] The microspheres obtained by spray drying were calcined at 550°C for 6 hours in air to obtain a zinc magnesium aluminate spinel composite ZrO2 and SiO2 carrier.

[0172] 143.17 g of praseodymium nitrate hexahydrate was dissolved in a certain amount of deionized water, with the water volume meeting the requirement of equal volume impregnation. The composite oxide support was added to the above solution and impregnated for 10 hours with equal volume. Then, it was sealed and activated in an oven at 55°C for 10 hours, then dried at 120°C for 4 hours, and finally calcined at 700°C for 5 hours to obtain the low-carbon alkane dehydrogenation catalyst.

[0173] The low-carbon alkane dehydrogenation catalyst prepared in this embodiment is supported by zinc magnesium aluminate spinel Zn. 0.5 Mg 0.5 A composite support of Al2O4, ZrO2, and SiO2. Based on the total mass of the active component and the support, the content of the active component is 15 wt%, and the content of the support is 85 wt%.

[0174] Comparative Example 1

[0175] The preparation process is basically the same as in Example 1, except that the support is a composite oxide support of Al2O3, ZrO2, and SiO2, and the proportion of ZrO2 and SiO2 in the support is the same as in Example 1. The preparation process of the support is as follows:

[0176] 441.84 g of aluminum nitrate nonahydrate, 53.05 g of zirconium oxychloride octahydrate, 146.77 g of hexadecyltrimethylammonium bromide (CTAB), and 161.26 g of urea were dissolved in 2416 g of deionized water and stirred until completely dissolved to obtain a transparent solution. This solution was placed in a high-pressure reactor and maintained at 120°C for 10 hours. The resulting slurry was washed with five times the volume of deionized water, and then filtered to form a filter cake.

[0177] The washed filter cake was re-pulped with deionized water, and then mixed with 50.05g of acidic silica sol (30% solid content), 7.51g of guar gum powder, and 4.50g of polyvinyl alcohol for 2 hours. After mixing, it was spray-dried with an inlet air temperature of 300℃, an outlet air temperature of 150℃, an atomizer speed of 40Hz, and a feed rate of 40rpm.

[0178] The microspheres obtained by spray drying were calcined at 650°C for 5 hours in air to obtain a composite oxide support of Al2O3, ZrO2, and SiO2.

[0179] The subsequent impregnation, drying, and calcination processes of the active components are the same as in Example 1.

[0180] Comparative Example 2

[0181] The preparation process is basically the same as in Example 1, except that the support is a composite oxide support of ZnAl2O4, ZrO2, and SiO2, and the proportion of ZrO2 and SiO2 in the support is the same as in Example 1. The preparation process of the support is as follows:

[0182] 194.96 g of zinc nitrate hexahydrate, 491.72 g of aluminum nitrate nonahydrate, and 53.06 g of zirconium oxychloride octahydrate were dissolved in 3835 g of deionized water along with 232.96 g of hexadecyltrimethylammonium bromide (CTAB) and 255.96 g of urea. The solution was stirred until completely dissolved, yielding a clear solution. This solution was placed in a high-pressure reactor and maintained at 120°C for 10 hours. The resulting slurry was washed with five times the volume of deionized water, and then filtered to form a filter cake.

[0183] The washed filter cake was re-pulped with deionized water, and then mixed with 50.05g of acidic silica sol (30% solid content), 7.51g of guar gum powder, and 4.50g of polyvinyl alcohol for 2 hours. After mixing, it was spray-dried with an inlet air temperature of 300℃, an outlet air temperature of 150℃, an atomizer speed of 40Hz, and a feed rate of 40rpm.

[0184] The microspheres obtained by spray drying were calcined at 650°C for 5 hours in air to obtain a composite oxide support of ZnAl2O4, ZrO2, and SiO2.

[0185] The subsequent impregnation, drying, and calcination processes of the active components are the same as in Example 1.

[0186] Comparative Example 3

[0187] The preparation process is basically the same as in Example 1, except that the support is only zinc magnesium aluminate spinel, and ZrO2 and SiO2 are no longer combined. The preparation process of the support is as follows:

[0188] 148.76 g of zinc nitrate hexahydrate, 51.29 g of magnesium nitrate hexahydrate, and 525.27 g of aluminum nitrate nonahydrate were dissolved in 3780 g of deionized water along with 229.62 g of hexadecyltrimethylammonium bromide (CTAB) and 252.29 g of urea. The solution was stirred until completely dissolved, yielding a clear solution. This solution was placed in a high-pressure reactor and maintained at 120°C for 10 hours. The resulting slurry was washed with five times the volume of deionized water, and then filtered to form a filter cake.

[0189] The washed filter cake was re-pulped with deionized water, and 6.01g of guar gum powder and 3.6g of polyvinyl alcohol were added and mixed for 2 hours before spray drying. The inlet air temperature of the spray dryer was 300℃, the outlet air temperature was 150℃, the atomizer speed was 40Hz, and the feed speed was 40rpm.

[0190] The microspheres obtained by spray drying were calcined at 650°C for 5 hours in air to obtain the carrier.

[0191] 3.95 g of ammonium metatungstate hydrate and 9.27 g of cerium nitrate hexahydrate were dissolved in a certain amount of deionized water, with the water volume meeting the requirement of equal volume impregnation. The composite oxide support was added to the above solution and impregnated for 10 hours with equal volume. Then, it was sealed and activated in a 50°C oven for 5 hours, then dried at 120°C for 4 hours, and finally calcined at 600°C for 4 hours to obtain the low-carbon alkane dehydrogenation catalyst.

[0192] The subsequent impregnation, drying, and calcination processes of the active components are the same as in Example 1.

[0193] Comparative Example 4

[0194] The preparation process is basically the same as in Example 1, except that the support is a physical mixture of zinc magnesium aluminate spinel, ZrO2, and SiO2. The preparation process of the support is as follows:

[0195] Preparation of zinc magnesium aluminate spinel: 148.76 g of zinc nitrate hexahydrate, 51.29 g of magnesium nitrate hexahydrate, and 525.27 g of aluminum nitrate nonahydrate were dissolved in 4076 g of deionized water with 229.62 g of hexadecyltrimethylammonium bromide (CTAB) and 252.29 g of urea. The solution was stirred until completely dissolved to obtain a transparent solution. This solution was placed in a high-pressure reactor and maintained at 120°C for 10 hours. The resulting slurry was washed with five times the volume of deionized water, and then filtered to form a filter cake.

[0196] The washed filter cake was re-pulped with deionized water, and 6.01g of guar gum powder and 3.6g of polyvinyl alcohol were added and mixed for 2 hours before spray drying. The inlet air temperature of the spray dryer was 300℃, the outlet air temperature was 150℃, the atomizer speed was 40Hz, and the feed speed was 40rpm.

[0197] The microspheres obtained by spray drying were calcined at 650°C for 5 hours in air to obtain zinc magnesium aluminate spinel.

[0198] Preparation of ZrO2: Dissolve 53.05 g of zirconium oxychloride octahydrate in deionized water. Add 25% ammonia solution dropwise while stirring, stopping the addition when the pH reaches 9-10. Continue stirring for 30 minutes, then allow to stand at room temperature for 2 hours. Wash the resulting slurry with five times the volume of deionized water, then filter to form a filter cake. Re-pulverize the washed filter cake with deionized water, add 0.75 g of guar gum powder and 0.45 g of polyvinyl alcohol, mix and stir for 2 hours, then spray dry under the same conditions as above.

[0199] Preparation of SiO2: Weigh 71.05g of sodium silicate nonahydrate, dissolve it in deionized water, stir until completely dissolved, slowly add 37% hydrochloric acid until the pH of the solution drops to 2.0-3.0, continue stirring for 30 minutes, let it stand at room temperature for 2 hours, wash the resulting slurry with five times the amount of deionized water, then filter to form a filter cake. Re-pulverize the washed filter cake with deionized water, add 0.75g of guar gum powder and 0.45g of polyvinyl alcohol, mix and stir for 2 hours, then spray dry under the same conditions as above.

[0200] The prepared Zn-Mg spinel was physically mixed with ZrO2 and SiO2 microspheres to obtain the carrier of this comparative example.

[0201] The subsequent impregnation, drying, and calcination processes of the active components are the same as in Example 1.

[0202] Comparative Example 5

[0203] The carrier and its preparation process are the same as in Example 1, except that the active components are not loaded.

[0204] Comparative Example 6

[0205] The preparation process is basically the same as in Example 2, except that the support is a composite oxide support of zinc magnesium aluminate spinel and ZrO2, and no longer contains SiO2. The preparation process of the support is as follows:

[0206] 89.26 g of zinc nitrate hexahydrate, 56.42 g of magnesium nitrate hexahydrate, 390.20 g of aluminum nitrate nonahydrate, and 70.36 g of zirconium oxychloride octahydrate were dissolved in 4160 g of deionized water, along with 156.90 g of sodium citrate and 160.24 g of urea. The mixture was stirred until completely dissolved, yielding a clear solution. This solution was placed in a high-pressure reactor and maintained at 110°C for 12 hours. The resulting slurry was washed with six times the volume of deionized water, and then filtered to form a filter cake.

[0207] The washed filter cake was re-slurryed with deionized water, and 6.64g of sodium carboxymethyl cellulose was added and mixed for 1 hour before spray drying. The spray drying, calcination process, and subsequent active component impregnation, drying, and calcination processes were the same as in Example 2.

[0208] Comparative Example 7

[0209] The preparation process is basically the same as in Example 2, except that the support is a composite oxide support of zinc magnesium aluminate spinel and SiO2, and no longer contains ZrO2. The preparation process of the support is as follows:

[0210] 89.26 g of zinc nitrate hexahydrate, 56.42 g of magnesium nitrate hexahydrate, 390.20 g of aluminum nitrate nonahydrate, 156.90 g of sodium citrate, and 160.24 g of urea were dissolved in 4161 g of deionized water and stirred until completely dissolved to obtain a transparent solution. This solution was placed in a high-pressure reactor and hydrothermally reacted at 110°C for 12 hours. The resulting slurry was washed with six times its volume of deionized water, and then filtered to form a filter cake.

[0211] The washed filter cake was re-pulped with deionized water, and then mixed with 106.22g of alkaline silica sol with a solid content of 25% and 6.64g of sodium carboxymethyl cellulose for 1 hour before spray drying.

[0212] The spray drying, calcination process, and subsequent active component impregnation, drying, and calcination processes are the same as in Example 2.

[0213] Comparative Example 8

[0214] The support was prepared using a conventional coprecipitation method, and the preparation process is as follows:

[0215] Dissolve 89.26g of zinc nitrate hexahydrate, 56.42g of magnesium nitrate hexahydrate, 390.20g of aluminum nitrate nonahydrate, and 70.36g of zirconium oxychloride octahydrate in 4600g of deionized water. Add 25% ammonia dropwise while stirring, and stop adding when the pH reaches 9-10. Continue stirring for 30 minutes, and let it stand at room temperature for 2 hours. Wash the resulting slurry with 6 times the volume of deionized water, and then filter to form a filter cake.

[0216] The washed filter cake was re-pulped with deionized water, and then mixed with 106.22g of alkaline silica sol with a solid content of 25% and 6.64g of sodium carboxymethyl cellulose for 1 hour before spray drying.

[0217] The spray drying, calcination process, and subsequent active component impregnation, drying, and calcination processes are the same as in Example 2.

[0218] Comparative Example 9

[0219] The preparation process is basically the same as in Example 2, except that the Zn:Mg molar ratio in the support is adjusted to 1:2, and the silicon content is increased to 30 wt% of the SiO2 content in the support. The preparation process is as follows:

[0220] 59.50 g of zinc nitrate hexahydrate, 102.58 g of magnesium nitrate hexahydrate, 450.23 g of aluminum nitrate nonahydrate, and 55.10 g of zirconium oxychloride octahydrate were dissolved in 4612 g of deionized water with 173.90 g of sodium citrate and 177.59 g of urea. The solution was stirred until completely dissolved, yielding a clear solution. This solution was placed in a high-pressure reactor and maintained at 110°C for 12 hours. The resulting slurry was washed with six times the volume of deionized water, and then filtered to form a filter cake.

[0221] The washed filter cake was re-slurried with deionized water, and then mixed with 187.15g of alkaline silica sol with a solid content of 25% and 7.80g of sodium carboxymethyl cellulose for 1 hour before spray drying. The inlet air temperature of the spray dryer was 350℃, the outlet air temperature was 170℃, the atomizer speed was 35Hz, and the feed rate was 60rpm.

[0222] The microspheres obtained by spray drying were calcined at 650°C for 4 hours in air to obtain a zinc magnesium aluminate spinel composite ZrO2 and SiO2 carrier.

[0223] 22.58 g of indium nitrate hydrate was dissolved in 100 ml of deionized water. The composite oxide support was added to the solution with stirring for 30 min and ultrasonication for 10 min. After that, it was impregnated for 12 hours, then sealed and activated in a 60 °C oven for 4 hours, then dried at 140 °C for 6 hours, and finally calcined at 650 °C for 4 hours to obtain the low-carbon alkane dehydrogenation catalyst.

[0224] Comparative Example 10

[0225] The preparation process is basically the same as in Example 2, except that the timing of adding the silicon source is adjusted. The preparation process is as follows:

[0226] 89.26 g of zinc nitrate hexahydrate, 56.42 g of magnesium nitrate hexahydrate, 390.20 g of aluminum nitrate nonahydrate, and 70.36 g of zirconium oxychloride octahydrate, along with 156.90 g of sodium citrate and 160.24 g of urea, were dissolved in 4161 g of deionized water and stirred until completely dissolved to obtain a transparent solution. Then, 106.22 g of alkaline silica sol with a solid content of 25% was added. The solution was placed in a high-pressure reactor and hydrothermally reacted at 110°C for 12 hours. The resulting slurry was washed with six times the volume of deionized water, and then filtered to form a filter cake.

[0227] The washed filter cake was re-pulped with deionized water, mixed with 6.64g of sodium carboxymethyl cellulose for 1 hour, and then spray-dried.

[0228] The spray drying, calcination process, and subsequent active component impregnation, drying, and calcination processes are the same as in Example 2.

[0229] The carriers prepared in the above embodiments and comparative examples were subjected to specific surface and pore volume tests, and the wear index was measured using a powder wear index tester. The data are shown in Table 1 below.

[0230]

[0231]

[0232] The test data in Table 1 show that the zinc magnesium aluminate spinel composite ZrO2 and SiO2 carrier prepared by the method of the present invention has a large specific surface area and pore volume, and a significantly reduced wear index. Based on these characteristics, the catalyst prepared by the method of the present invention can optimize the fluidization effect, improve heat transfer, reduce thermal collapse, and reduce catalyst loss when applied to a circulating fluidized bed device.

[0233] The catalysts prepared in the examples and comparative examples were subjected to propane dehydrogenation activity evaluation experiments under the following conditions: a fixed-bed reactor was used for evaluation. 3g of catalyst was loaded into a quartz reactor with an inner diameter of 8mm. Pure propane was introduced into the 400°C preheating zone via a mass flow meter and then into the reaction zone. No pre-reduction was performed. The reaction temperature was 610°C, the reaction pressure was 0.05MPa, and the propane mass hourly space velocity was 3h⁻¹. -1The single reaction time is 40 minutes, followed by regeneration. Regeneration is performed by first purging with a nitrogen-steam mixture (nitrogen comprising 50% of the mixture by mass) for 20 minutes, then introducing air and regenerating at a temperature of 650°C for 40 minutes. After purging with nitrogen-steam for 20 minutes, propane feed gas is introduced again for reaction. This regeneration process is repeated 50 times, with no further regeneration after the final reaction.

[0234] The catalyst removed after the reaction was subjected to thermogravimetric analysis to test the coke content. The changes in catalyst activity and coke amount are shown in Table 2.

[0235]

[0236] In addition, the catalysts prepared in the examples and comparative examples were subjected to isobutane dehydrogenation activity evaluation experiments under similar procedures. The difference from the propane dehydrogenation evaluation process was that the reaction temperature was 570°C and the mass hourly space velocity (WHSV) of isobutane was 2.5 h⁻¹. -1 The specific process is as follows: A fixed-bed reactor was used for evaluation. 3g of catalyst was loaded into a quartz reactor with an inner diameter of 8mm. Pure isobutane was introduced into a 400℃ preheating zone via a mass flow meter for heating, and then entered the reaction zone. No pre-reduction was performed. The reaction temperature was 570℃, the reaction pressure was 0.05MPa, and the mass hourly space velocity (HSV) of isobutane was 2.5h⁻¹. -1 The single reaction time is 40 minutes, followed by regeneration. Regeneration is performed by first purging with a nitrogen-steam mixture (nitrogen comprising 50% of the mixture by mass) for 20 minutes, then introducing air and maintaining the temperature at 650°C for 40 minutes. After purging with nitrogen-steam for 20 minutes, isobutane feed gas is introduced again for reaction. This regeneration process is repeated 50 times, with no further regeneration after the final reaction.

[0237] The catalyst removed after the reaction was subjected to thermogravimetric analysis to test the coke content. The changes in catalyst activity and coke amount are shown in Table 3.

[0238]

[0239] The activity evaluation data in Tables 1, 2, and 3 show that:

[0240] A comparison of Comparative Examples 1 and 2 with Example 1 shows that the Zn-containing x Mg y Catalysts supported on Al₂O₄ spinel exhibit high alkane conversion rates and olefin selectivity, due to the presence of Zn. x Mg yAl2O4 alters the inherent crystal phase structure, increasing oxygen vacancies and electron migration capacity through structural optimization, thus promoting the reaction. Furthermore, the reduction of acidic sites gives the catalyst better resistance to coking, significantly improving the stability of catalytic performance.

[0241] By comparing Comparative Example 3 with Example 1, the support containing both ZrO2 and SiO2 exhibits a larger specific surface area, higher pore volume, and a lower wear index compared to the support without ZrO2 and SiO2. Regarding alkane conversion and olefin selectivity, the support containing both ZrO2 and SiO2 demonstrates significantly better alkane conversion and olefin selectivity, as well as lower coke deposition, compared to the support without ZrO2 and SiO2.

[0242] A comparison of Comparative Examples 6 and 7 with Example 2 shows that, compared to catalysts supported on supports containing only ZrO2 or SiO2, supports containing both ZrO2 and SiO2 have a larger specific surface area and higher pore volume, or a lower wear index.

[0243] Furthermore, the catalysts in Examples 1-4 showed virtually no performance degradation after 50 regeneration cycles, indicating that the support prepared according to the method of this invention can maintain its interaction with the active components during multiple regeneration cycles. This is likely because the support prepared according to the method of this invention not only effectively improves alkane conversion and olefin selectivity, but also effectively extends the catalyst's lifespan and maintains high levels of alkane conversion and olefin selectivity. (Comparison) Figure 1 The two XRD diffraction patterns show that the composite oxide support in Example 1 and the Zn-Mg spinel support in Comparative Example 3 have basically the same XRD peak shapes. In the XRD pattern of the composite oxide support, the 2θ angle at 47-53° indicates a ZrO2 peak. This demonstrates that the homogeneous coprecipitation method ensures that ZrO2 is uniformly dispersed in the composite support and does not co-precipitate with other components to form new spinel structures or other structures. Furthermore, through... Figure 2 The XRD diffraction patterns show that the catalyst in Comparative Example 1, which uses a composite support containing Al2O3, ZrO2, and SiO2, exhibits significantly different XRD peak shapes compared to the catalysts in Examples 1, 3, and 4. The XRD peaks of the catalyst in Comparative Example 1 are mainly Al2O3 diffraction peaks, with weaker ZrO2 and SiO2 peaks also present; while the XRD peaks of Examples 1, 3, and 4 are mainly Zn... x Mg y The diffraction peaks of Al2O4 spinel, and Figure 1 The XRD peak shapes of the composite oxide support in Example 1 were consistent, and varied with the molar ratio of Zn to Mg and the Zn content. x Mg yThe intensity of the diffraction peaks varies slightly depending on the proportion of Al₂O₄ spinel. Furthermore, due to the good dispersion of the active component, there are no diffraction peaks corresponding to the oxides of the active component. Figure 2 It can also be seen that, due to the low SiO2 and ZrO2 content in Example 3, no obvious XRD diffraction peaks of ZrO2 and SiO2 appeared. In Example 4, with higher SiO2 and ZrO2 content, smaller SiO2 diffraction peaks appeared. In summary, this shows that according to the preparation method of the present invention, ZrO2 and SiO2 can be uniformly dispersed in the support.

[0244] In addition, accelerated aging tests were conducted on the catalysts of Examples 1, 3, 4, 8, and 9, respectively. Hydrothermal aging at 850°C for 24 hours was performed in a tubular furnace and a matching steam generator. The specific process was as follows: the catalyst was ground and sieved, placed in a quartz boat, and loaded into the center of the tubular furnace. A steam inlet (using deionized water) was connected to the tail gas condenser. Preheating was performed at a rate of 5-10°C / min to 150-200°C. After stabilization, steam was introduced, and the temperature was further increased at 3-5°C / min to 850°C. Once the target temperature was reached, steam was maintained, and aging was carried out at a constant temperature for 48 hours (temperature fluctuations were monitored within ±5°C). After aging, steam was shut off, and inert gas was used for purging. The temperature was then reduced to below 100°C at a rate of 5-10°C / min. After the reactor was completely cooled, the catalyst was removed. After accelerated aging, it was then loaded into a fixed-bed reactor for propane dehydrogenation evaluation experiments. The results are shown in Table 4 below.

[0245]

[0246] As can be clearly seen from the accelerated aging test data of the examples and comparative examples in Table 4 above, the catalysts of several comparative examples all showed varying degrees of performance degradation after hydrothermal aging, while the catalysts in Examples 1-4 of this invention maintained stable performance after hydrothermal aging at 850℃.

[0247] Based on the above activity evaluation data, post-reaction coke content, and hydrothermal aging test results, the catalyst prepared in this invention exhibits high conversion rate and high selectivity in the propane dehydrogenation to propylene reaction, and demonstrates excellent anti-coke performance and hydrothermal stability.

[0248] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A low-carbon alkane dehydrogenation catalyst, characterized in that, The catalyst includes an active component and a support; The active component includes one or more of the following metal oxides: In, W, Ce, Pr, Nd, and Ti; The content of the active component is 1-40 wt%, and the content of the carrier is 60-99 wt%, calculated based on the total mass of the active component and the carrier. The carrier is a composite carrier containing zinc magnesium aluminate spinel, ZrO2 and SiO2; the mass ratio of zinc magnesium aluminate spinel, ZrO2 and SiO2 is (50-98):(1-30):(1-20); The zinc magnesium aluminate spinel has the general formula Zn. x Mg y Al2O4, where: x+y=1, x≠0, y≠0, x≥y.

2. The low-carbon alkane dehydrogenation catalyst according to claim 1, characterized in that, The preparation of the carrier includes the following steps: S1. Prepare a solution containing soluble salts of zinc, magnesium, aluminum, and zirconium, a surfactant, and a homogeneous precipitant, and carry out a hydrothermal reaction; After the hydrothermal reaction is completed, the product is obtained by filtration and washing. S2. Mix the solvent with the hydrothermal product to obtain a slurry; then add a silicon source, binder, and pore expander, and dilute with solvent; subsequently perform spray drying and calcination to obtain a carrier.

3. A method for preparing a low-carbon alkane dehydrogenation catalyst, characterized in that, Including the following steps: S1. Prepare a solution containing soluble salts of zinc, magnesium, aluminum, and zirconium, a surfactant, and a homogeneous precipitant, and carry out a hydrothermal reaction; After the hydrothermal reaction is completed, the product is obtained by filtration and washing. S2. Mix the solvent with the hydrothermal products to obtain a slurry; then add a silicon source, binder, and pore expander, and dilute with solvent; subsequently, perform spray drying and calcination to obtain a carrier; S3. The support is impregnated with a solution containing metal ions; then activated, dried and calcined to obtain the low-carbon alkane dehydrogenation catalyst. The metal ions include one or more of In, W, Ce, Pr, Nd, and Ti.

4. The method for preparing the low-carbon alkane dehydrogenation catalyst according to claim 3, characterized in that, In S1, the molar ratio of zinc to magnesium is 1:(0.2-1); The ratio of aluminum to the total molar amount of zinc and magnesium is 1.8-2.5, calculated based on the total molar amount of zinc and magnesium.

5. The method for preparing the low-carbon alkane dehydrogenation catalyst according to claim 4, characterized in that, In S1, the molar ratio of zinc, magnesium, aluminum, zirconium, and surfactant to homogenizing precipitant and deionized water is 1:(0.2-0.5):(1-4):(80-500).

6. The method for preparing the low-carbon alkane dehydrogenation catalyst according to any one of claims 3 to 5, characterized in that, The mass of the zirconium is calculated according to ZrO2 and is denoted as m. Zr ; The quality of zinc, magnesium, and aluminum is based on Zn x Mg y Al2O4 calculation, denoted as m ZnMgAl ; The mass of silicon is calculated based on SiO2 and denoted as m. Si ; The mass of the carrier is according to m Zr m ZnMgAl m Si The sum is calculated and denoted as m. 载体 ; In S1, the amount of zirconium added is m. 载体 1-30 wt%; and / or, In S2, the m 载体 The mass ratio of adhesive and pore expander is 1:(0-0.1):(0-0.05); and / or, In S2, the amount of silicon added is m. 载体 1-20 wt%.

7. The method for preparing the low-carbon alkane dehydrogenation catalyst according to claim 6, characterized in that, In S1, the conditions for the hydrothermal reaction include: a holding temperature of 80-150℃; a holding time of 6-20 hours; and / or, In S2, the conditions for the calcination treatment include: a calcination holding temperature of 500-800℃; a calcination holding time of 2-8 hours; and / or, In S3, the conditions for the impregnation treatment include: an impregnation time of 4-24 hours; an impregnation temperature of 20-40°C; and / or, In S3, the activation conditions include: a temperature of 50-90℃ and a time of 2-10 hours; and / or, In S3, the conditions for the calcination treatment include: a calcination holding temperature of 500-800℃; a calcination holding time of 2-8 hours; and / or, In S3, the total amount is calculated based on the sum of the mass of the oxide corresponding to the metal and the carrier; the content of the oxide corresponding to the metal is 1-40 wt%, and the content of the carrier is 60-99 wt%.

8. The application of a low-carbon alkane dehydrogenation catalyst according to any one of claims 1 to 2, or a low-carbon alkane dehydrogenation catalyst prepared by any one of claims 3 to 7, in the dehydrogenation of low-carbon alkanes to olefins.

9. A method for dehydrogenating low-carbon alkanes to olefins using the low-carbon alkane dehydrogenation catalyst according to any one of claims 1 to 2, or using the low-carbon alkane dehydrogenation catalyst prepared by the method according to any one of claims 3 to 7, characterized in that, This includes the catalytic dehydrogenation of low-carbon alkanes to olefins under the action of the catalyst, wherein the reaction conditions include: The temperature is 540-640℃; The pressure is 0-0.1 MPa; The mass hourly space velocity (MSV) of low-carbon alkanes is 0.2–8 h⁻¹. -1 .

10. A method for regenerating a used catalyst, characterized in that, The used catalyst includes the low-carbon alkane dehydrogenation catalyst according to any one of claims 1-2 or the low-carbon alkane dehydrogenation catalyst prepared by the method according to any one of claims 3-7, and is the catalyst after the reaction of low-carbon alkane dehydrogenation to olefins; the regeneration includes the following steps: First, the catalyst that needs to be regenerated is purged with an inert gas containing water vapor. The purging temperature is 540-640℃ and the purging time is 10-30 minutes. Subsequently, air is introduced for high-temperature calcination, wherein the holding temperature for high-temperature calcination is 620-670℃ and the holding time is 10-240min; The inert gas containing water vapor has an inert gas content of 20-60 wt%.

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