Catalyst for catalytic conversion of propane to propylene acid and its use

Abstract

This invention relates to a catalyst for the catalytic production of acrylic acid from propane and its application, said catalyst being represented by the following general formula: Mo a V b Te c Nb d Ni e B f O x In this formula, a, b, c, d, e, and f represent the atomic numbers of Mo, V, Te, Nb, Ni, and B, respectively. The molar ratio of a:b:c:d:e:f is 9.5–10.1:2.2–2.5:2.0–2.3:1.8–2.0:0.1–1.0:0.05–0.85. The value of x is determined by the oxidation state of each element. Ni is introduced through nickel molybdate, and Mo is introduced through molybdate and the nickel molybdate itself. This invention, by introducing nickel into the catalyst using nickel molybdate, can adjust the content of metals with different valence states on the catalyst surface, thereby increasing the content of the high-valence element Mo in the catalyst. 6+ V 5+ and Ni 2+ The increased content enhances the redox ability of the catalyst, thereby improving the propane conversion activity.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a catalyst for the catalytic production of acrylic acid from propane and its application. Background Technology

[0002] Acrylic acid is an important organic chemical raw material and oilfield chemical additive. Driven by strong demand from four major sectors—construction, textiles, hygiene, and materials—China's acrylate market is experiencing rapid growth. China is the world's largest consumer and producer of acrylic acid, and is gradually developing towards large-scale, integrated industrial chain, and high-end products. Currently, the industrial synthesis of acrylic acid mainly uses propylene as a raw material, employing a two-step reaction: propylene first reacts with oxygen to produce acrolein, which is then oxidized to produce acrylic acid. While global propylene production capacity is growing slowly, demand is increasing rapidly, leading to a widening supply gap.

[0003] In the 21st century, petrochemical feedstocks will likely shift towards cheaper natural gas-based alkanes. Therefore, the shift in feedstock routes from olefins to alkanes will be a key focus of petrochemical technology research and development in the new century. Low-carbon alkanes are widely available globally, and converting them into high-value-added chemical products can bring significant economic benefits. The chemical conversion of low-carbon alkanes faces similar challenges: stable and inexpensive feedstocks, but difficult conversion, and the target products are relatively reactive and prone to further oxidation. Therefore, it is difficult to simultaneously achieve high conversion rates and selectivity for the target products of low-carbon alkane chemical conversions; a seesaw relationship is likely. To date, only a few reactions have achieved industrial-scale production, such as ethane steam cracking to ethylene, propane dehydrogenation to propylene, and butane selective oxidation to maleic anhydride. Alkane activation technologies that may be industrialized in the 21st century include ethane to acetic acid, isobutane to methacrylic acid, ethane catalytic dehydrogenation to ethylene, and propane to acrylic acid.

[0004] Propane is a key component of natural gas, liquefied petroleum gas (LPG), and coalbed methane. my country is a country with relatively abundant propane resources; for example, propane accounts for about 6% of oilfield gas, about 60% of LPG, and up to 15% of wet natural gas. Refinery gas also contains a certain amount of propane. A recent study by the World Energy Institute (WRI) indicates that China's shale gas reserves exceed 30 trillion cubic meters, ranking first in the world and almost twice that of the United States. With the accelerated exploitation of unconventional oil and gas resources such as shale gas, the potential supply of propane is substantial. These reserves are generally used as fuel or vented, resulting in significant resource waste. How to convert these low-carbon alkanes into high-value-added chemical products and reduce dependence on oil not only has enormous economic benefits but also potential social benefits in delaying oil depletion. Therefore, research on oxidative dehydrogenation to propylene, selective oxidation to acrolein, acrylic acid, isopropanol, and acetone, dehydrogenation aromatization, and ammonia oxidation to acrylonitrile are all of great significance.

[0005] The selective oxidation of propane to acrylic acid is a complex and integrated system process, and catalyst development is the core technology of the reaction process. In addition, reactor selection and design, reaction condition control, and product separation are also major research topics. To date, three catalyst systems exist for the selective oxidation of propane to acrylic acid: (1) industrial n-butane selective oxidation to maleic anhydride catalyst: VPO-based catalyst; (2) alkane oxidative dehydrogenation catalyst: heteropolyacid and its salt catalyst HxCs3-xPMo12O40 (x=0~3) (HPC); (3) propane ammoxidation and alkane oxidative dehydrogenation catalyst: composite metal oxide (MMO) catalyst. Most of the research on catalysts for the selective oxidation of propane to acrylic acid comes from these three catalyst systems.

[0006] VPO catalysts, developed in the 1970s, are a class of catalysts that have been very successful in oxidizing n-butane to maleic anhydride. In 1986, VPO catalysts were first applied to the selective oxidation of propane, producing acrylic acid and carbon oxides, but the yield of acrylic acid was quite low. Cheng Hua et al. obtained an acrylic acid yield of 18.8% and a selectivity as high as 68% by adding 0.01% Ce to the VPO catalyst, which is considered a relatively high acrylic acid yield. It has been reported that VPO catalysts containing Ce and La can be prepared using microwave heating. The results show that the catalyst composition n(P):n(V):n(La):n(Ce) = 1.1:1.0:0.04:0.04 has the highest propane conversion and acrylic acid selectivity, reaching 50.3% and 85.5%, respectively. X-ray diffraction and laser Raman spectroscopy analysis suggest that CeP5O... 14 The potential synergistic effect between the (VO)₂P₂O₇ phases can maintain catalyst stability and improve propane conversion and acrylic acid selectivity. Although this represents the best acrylic acid selectivity and yield among current VPO catalysts, the reaction temperature is relatively high, at 450℃. Based on existing research, there has been no breakthrough progress in the production of acrylic acid using VPO catalysts, and it is far from meeting the requirements for industrial-scale production.

[0007] HPC has its own advantages as a catalyst for the selective oxidation of propane to acrylic acid. Its structure is well-defined and its composition is simple. As a catalyst, HPC exhibits both acidic and redox properties, making it a bifunctional catalyst. However, this type of catalyst has poor stability and its activity decreases rapidly. This is because the Keggin-type anion of heteropolyacid catalysts undergoes structural decomposition in air at 400°C. Therefore, improving the thermal stability of HPC for the selective oxidation of propane is crucial. HPC prepared by Hong et al. x Cu 0.6 Cr 0.6 PMo 10 V2As 0.6 O40 The catalyst achieved the highest yield of acrylic acid (14.8%) in HPC systems to date, but no breakthrough has been achieved in applying HPC to the selective oxidation of propane to acrylic acid.

[0008] Composite metal oxide catalysts used for the selective oxidation of propane are mainly transition metal oxide catalysts. Compared with VPO and HPC catalysts, the structure-performance relationship of MMO catalysts is more complex. Due to the high-temperature calcination during their preparation, they exhibit good thermal stability. Currently, industrially used catalysts for the oxidation of propylene to acrolein and acrylic acid also belong to this system. In recent years, composite metal oxides have been found to have excellent catalytic effects on the selective oxidation of propane to acrylic acid, thus attracting attention and becoming a research hotspot. Currently, most composite metal oxides used for the oxidation of propane to acrylic acid are transition metal oxides, mainly including Mo-V-Sb, Mo-V-Te, Mo-V-Te-Nb, and Mo-V-Sb-Nb composite metal oxides. Mo-V-Te-Nb and Mo-V-Sb-Nb catalysts have been studied the most. Although these catalysts have complex preparation processes, numerous byproducts, and require further improvement in stability and reproducibility, they exhibit higher catalytic activity than VPO and HPA catalysts. They also possess higher reactivity and selectivity for the target product, higher thermal stability, less leaching of active components, and are less prone to carbon deposition at both low and high temperatures, making them more suitable as catalysts for the selective oxidation of propane to acrylic acid. Among the major catalyst systems applied to the selective oxidation of propane to acrylic acid, the Mo-V-Te-Nb catalytic system is currently considered the best due to its high reactivity and selectivity for the target product. Many researchers have conducted in-depth studies on its preparation methods and conditions, bulk and surface crystal structures, and catalytic kinetics. Currently, there are no reports of industrial applications of propane oxidation to acrylic acid, both domestically and internationally; it remains at the laboratory research stage.

[0009] Ushikubo et al. first discovered in 1997 that the Mo-V-Te-Nb-O catalyst system exhibited extremely high activity and selectivity for the selective ammoxidation of propane to acrylonitrile, with the highest acrylonitrile yield reaching nearly 50%. Mitsubishi Corporation of Japan was the first to develop MoV... 0.3 Te 0.23 Nb 0.l2 O x The catalyst is currently the best-performing composite metal oxide catalyst reported, achieving an acrylic acid yield of 48%. However, different researchers have prepared MoV catalysts... 0.3 Te 0.23 Nb 0.l2 O xThe yield of acrylic acid varies greatly depending on the catalyst. This is likely due to the large number of constituent elements in the catalyst and the complexity of the preparation process. Therefore, strictly controlling the preparation conditions of the catalyst is crucial to obtaining the desired acrylic acid.

[0010] Patent CN1596244A reports a method for producing acrylic acid from propane in the absence of molecular oxygen. The method involves passing a gas mixture containing propane, vapor, and inert gas in the absence of molecular oxygen through the catalyst reported in the patent. This method reduces the problem of high propionic acid content as a byproduct in the previous propane-to-acrylic acid process, significantly reduces the propionic acid / acrylic acid ratio at the reactor outlet, and also reduces the content of acetone as a byproduct. However, the yield of acrylic acid is only 10.5%.

[0011] Patent CN1326378A reports a catalytic system for the low-temperature partial oxidation of propane using a gas containing molecular oxygen, comprising Mo-V-Ga-Pd-Nb-X (where X = La, Te, etc.). This catalyst produces acrylic acid at low temperatures via the gas-phase partial oxidation of propane, at temperatures of 200°C–300°C, atmospheric pressure, and a reaction space velocity of 200–3000 L / kg. -1 h -1 Under these conditions, propane conversion is 10%-25%, and acrylic acid selectivity is 20%-45%.

[0012] Patent CN102179261A reports a method for catalyzing the oxidation of propane to prepare acrylic acid using Mo, V, Te, and Nb as active components. This patent provides a template synthesis method for preparing a composite metal oxide catalyst for the selective oxidation of propane to acrylic acid with a periodic and regular ordered structure, which solves the problems of large particle size and uneven structure in the previous catalyst preparation process. The highest conversion rate of propane is 68.3%, and the yield of acrylic acid is about 45%. However, the template synthesis method results in a high preparation cost.

[0013] Patent CN114534750A discloses a method for preparing a catalyst for the selective oxidation of propane to acrylic acid. By fixing the molar ratio of several active components (Mo-V-Te-Nb) and adding the promoter NiSb₂O₆ to the Mo-V-Te-Nb active components, the activity, selectivity, and stability of the catalyst are effectively improved. The introduction of the NiSb₂O₆ structure helps reduce the total acid content on the catalyst surface. The NiSb₂O₆ involved in this method needs to be obtained by high-temperature calcination above 800℃, then mixed with the Mo-V-Te-Nb active components, followed by granulation, molding, drying, and calcination to obtain the catalyst. Therefore, the catalyst preparation process requires two calcinations, resulting in a long preparation process and high manufacturing costs. Summary of the Invention

[0014] The purpose of this invention is to provide a catalyst for the catalytic production of acrylic acid from propane, in order to solve the problems of long catalyst preparation process and severe deep oxidation of products in the prior art, and to further expand the industrial application value of Mo-V system composite metal oxide catalysts.

[0015] Another objective of this invention is to provide an application of a propane-to-acrylic acid catalyst in a slurry bed reactor.

[0016] To achieve the above objectives, the present invention provides a catalyst for the catalytic production of acrylic acid from propane, the catalyst being represented by the following general formula:

[0017] Mo a V b Te c Nb d Ni e B f O x

[0018] Wherein, a, b, c, d, e, and f represent the atomic number of Mo, V, Te, Nb, Ni, and B, respectively, and in molar ratio, a:b:c:d:e:f is 9.5–10.1:2.2–2.5:2.0–2.3:1.8–2.0:0.1–1.0:0.05–0.85, and the value of x is determined by the oxidation state of each element; Ni is introduced through nickel molybdate, and Mo is introduced through molybdate and the nickel molybdate, wherein the nickel molybdate is prepared by co-precipitation of molybdate and nickel salt in the presence of organic acid.

[0019] The propane-to-acrylic acid catalyst of the present invention is prepared by the following method:

[0020] 1) Dissolve and mix molybdate, vanadate, tellurium compound, niobium salt, and boride evenly, and co-precipitate to form a slurry. After drying and pulverizing, prepare the Mo-V-Te-Nb-B component; 2) Mix organic acid, nickel salt, molybdate, and deionized water evenly, and then dry, calcine, and pulverize to obtain nickel molybdate component; 3) Mix Mo-V-Te-Nb-B component and nickel molybdate component, and after dry mixing of materials, add binder and deionized water and stir to form a slurry. Then, after molding, drying, and calcining, obtain the catalyst.

[0021] The catalyst for the propane-to-acrylic acid production of the present invention has a calcination temperature of 600°C or higher in step 3).

[0022] In the propane-catalyzed production of acrylic acid catalyst of the present invention, in step 2), organic acid, nickel salt, molybdate and deionized water are mixed in a pH range of 2 to 5.

[0023] In the propane-to-acrylic acid catalyst of the present invention, in step 1), the molybdate is one of ammonium heptamolybdate and ammonium tetramolybdate, the vanadate is one of ammonium metavanadate and vanadium oxalate, the tellurium compound is one of telluric acid and tellurium dioxide, the niobium salt is one of niobium oxalate, niobium acetate, and ammonium niobium oxalate, and the boride is boric anhydride or boric acid; in step 2), the organic acid is one of oxalic acid and citric acid, and the nickel salt is one of nickel acetate, nickel nitrate, and basic nickel carbonate.

[0024] In the propane-to-acrylic acid catalyst of the present invention, the binder in step 3) is one or more of silica sol, alumina sol and aluminosilicate sol, preferably silica sol.

[0025] The catalyst for the propane-to-acrylic acid production of the present invention, wherein in step 3), the amount of binder added is 10wt% to 20wt% of the total amount of Mo-V-Te-Nb-B component and nickel molybdate component, and the amount of deionized water added is 30wt% to 40wt% of the total amount of Mo-V-Te-Nb-B component and nickel molybdate component.

[0026] To achieve the above objectives, the present invention also provides an application of the above-mentioned catalyst in a slurry bed reactor, wherein a mixture of deionized water, propane, oxygen and nitrogen passes through a slurry bed containing fine catalyst particles in a bubbling manner, and the slurry temperature in the slurry bed reactor is 430°C to 500°C.

[0027] The catalyst described in this invention is used in a slurry bed reactor. During the reaction, the total mass hourly space velocity is 1000 ml / (g·h) to 3000 ml / (g·h), the oxygen / propane volume ratio is 1 to 5, the water / propane volume ratio is 1 to 5, and the remainder is nitrogen.

[0028] In the application of the catalyst described in this invention in a slurry bed reactor, propane is present at a concentration of 5 vol% to 15 vol% of the total gas volume.

[0029] Beneficial effects of this invention:

[0030] The catalyst of this invention uses self-made nickel molybdate as an auxiliary active component. Nickel is introduced into the catalyst through nickel molybdate, which is prepared by co-precipitation of molybdate and nickel salt in the presence of organic acid. The carboxyl groups in the organic acid can disperse the lattice clusters, making the nickel molybdate oxide "fine-crystalized". This allows for the adjustment of the content of metals with different valence states on the catalyst surface, enabling the high-valence element Mo to be present in the catalyst. 6+ V 5+ and Ni 2+The increased content of nickel molybdate enhances the redox capacity of the catalyst, thereby improving its propane conversion activity. Furthermore, this nickel molybdate does not require high-temperature calcination; it can be prepared by mixing it with the Mo-V-Te-Nb-B component after low-temperature drying, simplifying the preparation process.

[0031] Traditional processes using tubular fixed-bed reactors suffer from difficulty in controlling localized temperatures at different locations within the catalyst bed, leading to "temperature runaway" phenomena that are detrimental to stable operation. In contrast, slurry-bed reactors utilize a liquid medium with a high heat capacity, ensuring uniform heat distribution within the reactor during propane oxidation. This reduces the likelihood of temperature runaway in the catalyst bed, and the use of fine-particle catalysts eliminates the influence of internal diffusion, effectively resolving issues such as excessively high localized hot spots and carbon buildup that commonly occur in tubular fixed-bed reactors.

[0032] Compared to fixed-bed reactors, deep oxidation of the product cannot be suppressed in slurry-bed reactors by adjusting catalyst concentrations in different reaction sections. To further improve product selectivity, the selectivity of acrylic acid needs to be enhanced by controlling the surface acidity of the catalyst. Boron doping reduces the acid strength of both strong and weak acid centers on the catalyst surface, decreasing the total acid integral and thus inhibiting deep oxidation of the acrylic acid product. The optimal distribution of Mo-V-Te-Nb-B active centers and nickel molybdate active centers in the surface crystal structure allows for synergistic effects on reactant and intermediate product molecules, completing the full propane-to-acrylic acid conversion process. This provides the catalyst with suitable surface acidity and redox capabilities, resulting in a favorable redox conversion, which is essential for high catalytic activity. Attached Figure Description

[0033] Figure 1 These are H2-TPR characterization diagrams of the catalysts obtained in Example 2 and Comparative Example 2.

[0034] Figure 2 These are NH3-TPD characterization diagrams of the catalysts obtained in Example 2 and Comparative Example 1. Detailed Implementation

[0035] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0036] Example 1

[0037] Preparation of catalyst 1

[0038] Step 1: Preparation of the catalyst slurry of the present invention by dissolution-coprecipitation method 1-1

[0039] Add 141.5g of ammonium heptamolybdate, 22.2g of ammonium metavanadate, 39.9g of telluric acid, 0.3g of boric acid and 40ml of water to beaker No. 1. Stir the mixture at 75-80℃ to dissolve it. Add 82.2g of niobium oxalate and 100ml of distilled water to beaker No. 2. Stir the mixture at 75-80℃ to dissolve it. Then slowly add the solution in beaker No. 2 dropwise to beaker No. 1. Continue to add distilled water to 100ml. React at atmospheric pressure for 2h to obtain a multi-component composite metal oxide catalyst slurry 1-1.

[0040] Step 2: Preparation of nickel molybdate component 1-2

[0041] In beaker No. 3, 25g of oxalic acid, 12.7g of ammonium heptamolybdate, and 50ml of deionized water are mixed evenly in a 100ml beaker. In beaker No. 4, 3.0g of nickel nitrate is dissolved in 10ml of deionized water. The solution in beaker No. 4 is then added dropwise to beaker No. 3. The pH of the solution is adjusted to 2 with ammonia. After mixing, the mixture is reacted at 55-60℃ and normal pressure for 2.5h to obtain a slurry containing nickel molybdate. This slurry 1-2 is first dried in an oven at 80℃ for 16h, and then dried at 120℃ for 1.5h. After grinding and pulverizing, it forms 50-100 mesh particles, which is nickel molybdate component 1-2.

[0042] Step 3: Catalyst preparation

[0043] The slurry 1-1 is dried and then crushed and ground to form active component particles 1-3 of 50-100 mesh. These active component particles 1-3 are mixed with 1-2 and dry-mixed for 1.0 h. Silica sol and deionized water are then added to the mixture to form a slurry. The amount of silica sol added is 20% of the mass of the solid powder, and the amount of deionized water added is 40% of the mass of the solid powder. The slurry is spray-dried at 180°C, calcined in air at 200°C for 3 h, and calcined in nitrogen at 650°C for 2 h. The slurry is then sieved to obtain catalyst particles of 40-80 mesh to obtain catalyst 1, with a Mo:V:Te:Nb:Ni:B ratio of 10.1:2.2:2.0:1.8:0.1:0.06.

[0044] Step 4: Performance testing of catalyst 1

[0045] Propane oxidation to acrylic acid method: 10 ml of catalyst was loaded into a slurry bed reactor. Liquid paraffin was used as the inert medium. Under stirring, the catalyst particles were suspended in the inert medium of liquid paraffin. Deionized water was vaporized through a heating tube at 150°C and then mixed with propane, oxygen and nitrogen. The raw materials were passed through the slurry bed reactor in the form of bubbles. The oxidation reaction was carried out for 24 h according to the conditions listed in Table 1. The product was condensed and collected to obtain the target product acrylic acid. The test results are shown in Table 2.

[0046] Table 1 Process parameters for propane oxidation to acrylic acid

[0047]

[0048] Table 2

[0049]

[0050] Implementation Example 2

[0051] Preparation of catalyst 2

[0052] The preparation steps of catalyst 2 are the same as in Example 1.

[0053] Step 2: Preparation of nickel molybdate component 1-2

[0054] In beaker No. 3, mix 8g of oxalic acid, 12.7g of ammonium heptamolybdate, and 50ml of deionized water in a 100ml beaker until homogeneous. In beaker No. 4, dissolve 3.0g of nickel nitrate in 10ml of deionized water. Then, add the solution from beaker No. 4 dropwise to beaker No. 3. Adjust the pH of the solution to 5 with ammonia water. After mixing, react at 55-60℃ and normal pressure for 2.5h to obtain a slurry containing nickel molybdate. First, dry the slurry 1-2 in an oven at 80℃ for 16h, and then continue drying at 120℃ for 1.5h. After grinding and pulverizing, form 50-100 mesh particles, which is nickel molybdate component 1-2.

[0055] Step 3: Preparation of finished catalyst 2

[0056] The active component particles obtained in the first step were dried, crushed, and ground to form 50-100 mesh active component particles 1-3. These particles were then mixed with the nickel molybdate obtained in the second step and added to a kneading device. After dry mixing for 1.0 h, deionized water and silica sol were added to the mixture to form a slurry. The amount of silica sol added was 10% of the mass of the solid powder, and the amount of deionized water added was 30% of the mass of the solid powder. The slurry was spray-dried at 180°C and calcined at 600°C under a nitrogen atmosphere for 2 hours. The sieving yielded catalyst particles of 40-80 mesh, thus producing catalyst 2, with a Mo:V:Te:Nb:Ni:B ratio of 10.1:2.2:2.0:1.8:0.1:0.06. The oxidation reaction was carried out for 24 h according to condition 2 listed in Table 1, and the test results are shown in Table 5.

[0057] Comparative Example D1

[0058] Similar to Example 2, except that in the first step, the catalyst slurry 1-1 was prepared by dissolution-coprecipitation without the addition of boric acid, while the amounts of other substances added were the same; then it was mixed with nickel molybdate component 1-2 to obtain the comparative catalyst D1, with the composition of Mo:V:Te:Nb:Ni = 10.1:2.2:2.0:1.8:0.1. The oxidation reaction was carried out for 24 hours according to condition 2 listed in Table 1, and the test results are shown in Table 5.

[0059] Comparative Example D2

[0060] Similar to Example 2, the amount of catalyst slurry 1-1 prepared by the dissolution-coprecipitation method in the first step is the same. The difference is that nickel molybdate prepared in the second step is not included. The catalyst preparation method in the third step is as follows: the slurry 1-1 is dried and then crushed and ground to form active component particles 1-3 of 50-100 mesh. Silica sol and deionized water are added to form a slurry. The slurry is then spray-dried at 180°C, calcined in air at 200°C for 3 hours, and calcined in nitrogen at 650°C for 2 hours. Catalyst particles of 40-80 mesh are obtained by sieving, and comparative catalyst D2 is prepared. The composition of the prepared catalyst is Mo:V:Te:Nb:B = 9.8:2.3:2.1:1.9:0.06. The oxidation reaction is carried out for 24 hours according to condition 2 listed in Table 1. The test results are shown in Table 5.

[0061] Comparative Example D3

[0062] Add 154.2g of ammonium tetramolybdate, 28.6g of ammonium metavanadate, 54.0g of telluric acid and 40ml of water to beaker No. 1. Stir the mixture at 75-80℃ to dissolve it. Add 109.8g of niobium oxalate and 50ml of distilled water to beaker No. 2. Stir the mixture at 75-80℃ to dissolve it. Then slowly add the solution in beaker No. 2 dropwise to beaker No. 1. Continue to add distilled water to 100ml. React at atmospheric pressure for 2 hours to obtain a multi-component composite metal oxide catalyst slurry.

[0063] The above slurry was dried and then crushed and ground to form active component particles of 50-100 mesh. Silica sol was added to the active component particles at a weight of 20% of the particle weight, and water was added at a weight of 40% of the particle weight. The mixture was kneaded to form a paste. The slurry was spray-dried at 180°C, calcined in air at 200°C for 3 hours, and then calcined in nitrogen at 600°C for 2 hours. The resulting catalyst particles were sieved to obtain catalyst particles of 40-80 mesh, yielding catalyst D3 with a Mo:V:Te:Nb ratio of 9.8:2.4:2.3:2.0.

[0064] The performance of catalyst D3 in the synthesis of acrylic acid from propane was tested. The oxidation reaction was carried out for 24 hours according to condition 2 listed in Table 1. The test results are shown in Table 5.

[0065] Comparative Example D4

[0066] The first step is the same as in Example 2. The active component particles obtained in the first step are dried and then crushed and ground so that all the blocky material is formed into 50-100 mesh active component particles 1-3.

[0067] Step 2: Use commercially available nickel molybdate (manufacturer: Alfa, item number: 089938, purity: 98%).

[0068] 2.2g of nickel molybdate was uniformly mixed with the active component particles 1-3 obtained in the first step and added to a kneading device. After dry mixing for 1.0h, deionized water and silica sol were added to the mixture to form a slurry. The amount of silica sol added was 10% of the mass of the above solid powder, and the amount of deionized water added was 30% of the mass of the above solid powder. The slurry was spray-dried at 180℃ and calcined at 600℃ under a nitrogen atmosphere for 2 hours. The catalyst particles of 40-80 mesh were obtained by sieving, and the catalyst was prepared with the composition Mo:V:Te:Nb:Ni:B = 10.0:2.3:2.1:1.9:0.12:0.06.

[0069] The catalyst performance was evaluated according to the catalyst performance test method in Example 2, and the experimental results are shown in Table 5.

[0070] Figure 1 Table 3 shows the H2-TPR characterization diagrams of Example 2 and Comparative Example 2; Table 3 shows the XPS characterization data of Example 2 and Comparative Example 2. Figure 2 Table 4 shows the NH3-TPD characterization diagrams of Example 2 and Comparative Example 1; Table 4 shows the catalyst surface acidity integral data of Example 2 and Comparative Example 1.

[0071] from Figure 1 As shown in Table 3, the introduction of nickel molybdate plays a role in regulating the content of metals with different valence states on the catalyst surface, thereby increasing the content of high-valence elements such as Mo in the catalyst. 6+ V 5+ and Ni 2+ With increased content, the redox ability of the catalyst is enhanced; from Figure 2 As shown in Table 4, before the addition of B, the catalyst contained two ammonia desorption peaks, with peak temperatures around 190℃ and 450℃, respectively. This indicates the presence of both weak and strong acid sites on the catalyst surface. After the addition of B, the desorption temperatures of both weak and strong acid sites gradually decreased. This suggests that the doping of B reduced the strength of strong and weak acid sites on the catalyst. The total acid content on the catalyst surface was calculated (Table 4), indicating that the introduction of B reduced the total acid content on the catalyst surface, thereby improving the selectivity of acrylic acid.

[0072] Table 3 XPS test results of the catalyst

[0073]

[0074] Table 4. Surface acidity potential integration results of the catalyst.

[0075]

[0076] Example 3

[0077] Preparation of catalyst 3

[0078] The preparation steps of catalyst 3 are the same as those in Example 1, specifically the first and third steps.

[0079] Step 2: Preparation of nickel molybdate component 1-2

[0080] In beaker No. 3, 20g of citric acid, 12.7g of ammonium molybdate, and 50ml of deionized water are mixed evenly in a 100ml beaker. In beaker No. 4, 3.0g of nickel nitrate is dissolved in 10ml of deionized water. The solution in beaker No. 4 is then added dropwise to beaker No. 3. The pH of the solution is adjusted to 3 with ammonia. After mixing, the mixture is reacted at 55-60℃ and normal pressure for 1 hour to obtain a slurry containing nickel molybdate. This slurry 1-2 is dried at 120℃ for 10 hours, and then ground and pulverized to form 50-100 mesh particles, which is nickel molybdate component 1-2.

[0081] The catalyst 3 was prepared with the following composition: Mo:V:Te:Nb:Ni:B = 10.1:2.2:2.0:1.8:0.1:0.06.

[0082] The oxidation reaction was carried out for 24 hours according to condition 1 listed in Table 1, and the test results are shown in Table 5.

[0083] Example 4

[0084] Preparation of catalyst 4

[0085] Step 1: Preparation of the catalyst slurry of the present invention by dissolution-coprecipitation method 1-1

[0086] Add 156.9g of ammonium tetramolybdate, 35.5g of vanadium oxalate, 55.0g of telluric acid, 4.4g of boric anhydride and 200ml of water to beaker No. 1. Stir the mixture at 75-80℃ to dissolve it. Add 61.5g of ammonium niobate oxalate and 100ml of distilled water to beaker No. 2. Stir the mixture at 75-80℃ to dissolve it. Then slowly add the solution in beaker No. 2 dropwise to beaker No. 1. Continue to add distilled water to 100ml. React at atmospheric pressure for 2h to obtain a multi-component composite metal oxide catalyst slurry 1-1.

[0087] Step 2: Preparation of nickel molybdate component 1-2

[0088] In beaker No. 3, 25g of oxalic acid, 8.2g of ammonium tetramolybdate, and 50ml of deionized water were mixed evenly in a 100ml beaker. In beaker No. 4, 15.1g of nickel nitrate was dissolved in 10ml of deionized water. The solution in beaker No. 4 was then added dropwise to beaker No. 3. The pH of the solution was adjusted to 4 with ammonia. After mixing, the mixture was reacted at 55-60℃ and normal pressure for 2.5h to obtain a slurry containing nickel molybdate. The slurry 1-2 was first dried in an oven at 80℃ for 16h, and then dried at 120℃ for 1.5h. After grinding and pulverizing, 50-100 mesh particles were formed, which is nickel molybdate component 1-2.

[0089] Step 3: Catalyst preparation

[0090] The slurry 1-1 is dried and then crushed and ground to form active component particles 1-3 of 50-100 mesh. These active component particles 1-3 are mixed with 1-2 and dry-mixed for 1.0 h. Silica sol and deionized water are then added to the mixture to form a slurry. The amount of silica sol added is 20% of the mass of the solid powder, and the amount of deionized water added is 40% of the mass of the solid powder. The slurry is spray-dried at 180°C, calcined in air at 200°C for 3 h, and calcined in nitrogen at 650°C for 2 h. The sieving yields catalyst particles of 40-80 mesh, and the catalyst is obtained. The molar ratio of Mo, V, Te, Nb:Ni:B is 10.1:2.2:2.3:1.92:0.5:0.84.

[0091] The oxidation reaction was carried out for 24 hours according to condition 4 listed in Table 1, and the test results are shown in Table 5.

[0092] Example 5

[0093] Preparation of catalyst 5

[0094] Step 1: Preparation of the catalyst slurry of the present invention by dissolution-coprecipitation method 1-1

[0095] Add 156.9g of ammonium tetramolybdate, 43.7g of vanadium oxalate, 59.4g of telluric acid, 2.9g of boric anhydride and 200ml of water to beaker No. 1. Stir the mixture at 75-80℃ to dissolve it. Add 67.7g of ammonium niobate and 100ml of distilled water to beaker No. 2. Stir the mixture at 75-80℃ to dissolve it. Then slowly add the solution in beaker No. 2 dropwise to beaker No. 1. Continue to add distilled water to 100ml. React at atmospheric pressure for 2 hours to obtain a multi-component composite metal oxide catalyst slurry 1-1.

[0096] Step 2: Preparation of nickel molybdate component 1-2

[0097] In beaker No. 3, 20g of oxalic acid, 9.2g of ammonium tetramolybdate, and 50ml of deionized water were mixed evenly in a 100ml beaker. In beaker No. 4, 34.2g of nickel nitrate was dissolved in 10ml of deionized water. The solution in beaker No. 4 was then added dropwise to beaker No. 3. The pH of the solution was adjusted to 4 with ammonia. After mixing, the mixture was reacted at 55-60℃ and normal pressure for 2.5h to obtain a slurry containing nickel molybdate. The slurry 1-2 was first dried in an oven at 80℃ for 16h, and then dried at 120℃ for 1.5h. After grinding and pulverizing, 50-100 mesh particles were formed, which is nickel molybdate component 1-2.

[0098] Step 3: Catalyst preparation

[0099] The slurry 1-1 is dried and then crushed and ground to form active component particles 1-3 of 50-100 mesh. These active component particles 1-3 are mixed with 1-2 and dry-mixed for 1.0 h. Silica sol and deionized water are then added to the mixture to form a slurry. The amount of silica sol added is 20% of the mass of the solid powder, and the amount of deionized water added is 40% of the mass of the solid powder. The slurry is spray-dried at 180°C, calcined in air at 200°C for 3 h, and calcined in nitrogen at 650°C for 2 h. The sieving yields catalyst particles of 40-80 mesh, and the catalyst is obtained. The molar ratio of Mo, V, Te, Nb:Ni:B is 9.5:2.5:2.3:2.0:1.0:0.5.

[0100] The oxidation reaction was carried out for 24 hours according to condition 1 listed in Table 1, and the test results are shown in Table 5.

[0101] Example 6

[0102] Preparation of catalyst 6

[0103] Step 1: Preparation of the catalyst slurry of the present invention by dissolution-coprecipitation method 1-1

[0104] 141.5g of ammonium heptamolybdate, 22.2g of ammonium metavanadate, 43.6g of telluric acid, 1.6g of boric acid, and 200ml of water were mixed and stirred at 75-80℃ to dissolve. 93.2g of niobium oxalate and 200ml of distilled water were added to beaker No. 2 and stirred at 75-80℃ to dissolve. The solution in beaker No. 2 was then slowly added dropwise to beaker No. 1, and distilled water was added until 100ml was reached. The mixture was reacted at atmospheric pressure for 2 hours to obtain a multi-component composite metal oxide catalyst slurry 1-1.

[0105] Step 2: Preparation of nickel molybdate component 1-2

[0106] In beaker No. 3, 15g of oxalic acid, 6.7g of ammonium heptamolybdate, and 50ml of deionized water were mixed evenly in a 100ml beaker. In beaker No. 4, 11.0g of nickel nitrate was dissolved in 10ml of deionized water. The solution in beaker No. 4 was then added dropwise to beaker No. 3. The pH of the solution was adjusted to 4 with ammonia. After mixing, the mixture was reacted at 55-60℃ and normal pressure for 2.5h to obtain a slurry containing nickel molybdate. The slurry 1-2 was first dried in an oven at 80℃ for 16h, and then dried at 120℃ for 1.5h. After grinding and pulverizing, it formed 50-100 mesh particles, which is nickel molybdate component 1-2.

[0107] Step 3: Catalyst preparation

[0108] The slurry 1-1 is dried and then crushed and ground to form active component particles 1-3 of 50-100 mesh. These active component particles 1-3 are mixed with 1-2 and dry-mixed for 1.0 h. Silica sol and deionized water are then added to the mixture to form a slurry. The amount of silica sol added is 20% of the mass of the solid powder, and the amount of deionized water added is 40% of the mass of the solid powder. The slurry is spray-dried at 180°C and calcined at 650°C under a nitrogen atmosphere for 2 hours. The sieving yields catalyst particles of 40-80 mesh, and the catalyst is prepared. The molar ratio of Mo, V, Te, Nb:Ni:B is 9.6:2.2:2.2:1.9:0.4:0.3.

[0109] The oxidation reaction was carried out for 24 hours according to condition 2 listed in Table 1, and the test results are shown in Table 5.

[0110] Table 5

[0111]

[0112] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A catalyst for the catalytic conversion of propane to propylene acid, characterized in that, The catalyst is represented by the following general formula: Mo a V b Te c Nb d Ni e B f O x In the formula, a, b, c, d, e, f represent the atomic number of Mo, V, Te, Nb, Ni, B respectively, and a:b:c:d:e:f is 9.5-10.1:2.2-2.5:2.0-2.3:1.8-2.0:0.1-1.0:0.05-0.85 in terms of molar ratio, and the value of x is determined by the oxidation state of each element; Ni is introduced by nickel molybdate, Mo is introduced by molybdate and the nickel molybdate, which is prepared by co-precipitation of molybdate and nickel salt in the presence of organic acid.

2. The catalyst for the catalytic production of propylene acid from propane according to claim 1, characterized by that, The catalyst is prepared by the following method: 1) Dissolve and mix uniformly molybdate, vanadate, tellurium compound, niobium salt and boride, form slurry after co-precipitation, and then prepare Mo-V-Te-Nb-B component by drying and crushing; 2) Mix uniformly organic acid, nickel salt, molybdate and deionized water, and then obtain nickel molybdate component by drying, calcination and crushing; 3) Mix Mo-V-Te-Nb-B component and nickel molybdate component, add binder and deionized water to form slurry after material dry mixing, and then obtain catalyst by molding, drying and calcination.

3. The catalyst for the catalytic production of propylene acid from propane according to claim 2, characterized by that, The calcination temperature in step 3) is greater than or equal to 600℃.

4. The catalyst for the catalytic production of propylene acid from propane according to claim 2, characterized by that, The organic acid, nickel salt, molybdate and deionized water in step 2) are mixed at pH 2-5.

5. The catalyst for the catalytic production of propylene acid from propane according to claim 2, characterized by that, In step 1), the molybdate is one of ammonium heptamolybdate and ammonium tetramolybdate, the vanadate is one of ammonium metavanadate and vanadyl oxalate, the tellurium compound is one of telluric acid and tellurium dioxide, the niobium salt is one of niobium oxalate, niobium acetate and ammonium niobium oxalate, and the boride is boric anhydride or boric acid; in step 2), the organic acid is one of oxalic acid and citric acid, and the nickel salt is one of nickel acetate, nickel nitrate and basic nickel carbonate.

6. The catalyst for the catalytic production of propylene acid from propane according to claim 2, characterized by that, The binder in step 3) is one or more of silica sol, aluminum sol and silica-aluminum sol.

7. The catalyst for the catalytic production of propylene acid from propane according to claim 2, characterized by that, The binder in step 3) is silica sol.

8. The catalyst for the catalytic production of propylene acid from propane according to claim 2, characterized by that, In step 3), the amount of binder added is 10wt%-20wt% of the total amount of Mo-V-Te-Nb-B component and nickel molybdate component, and the amount of deionized water added is 30wt%-40wt% of the total amount of Mo-V-Te-Nb-B component and nickel molybdate component.

9. Use of a catalyst according to any one of claims 1 to 8 in a slurry reactor, characterized in that, The mixture of deionized water, propane, oxygen and nitrogen passes through the slurry layer in which catalyst fine particles are suspended in the form of bubbling, and the slurry temperature in the slurry bed reactor is 430℃-500℃.

10. Use of the catalyst according to claim 9 in a slurry reactor, characterized in that, During the reaction, the total mass space velocity is 1000ml / (g•h)-3000ml / (g•h), the oxygen / propane volume ratio is 1-5, the water / propane volume ratio is 1-5, and the rest is nitrogen.

11. Use of the catalyst according to claim 9 in a slurry reactor, characterized in that, The amount of propane is 5vol%-15vol% of the total gas amount.

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