Catalyst for catalytic synthesis of acrylic acid from propane and its use

Abstract

The application relates to a catalyst for catalytically synthesizing propylene acid from propane and application thereof, and the catalyst is represented by the following general formula: Mo a V b Te c Nb d Ni e O x Wherein, a, b, c, d and e respectively represent the atom numbers of Mo, V, Te, Nb and Ni, and the molar ratio of a:b:c:d:e is 7.0-9.0:1.7-2.5:1.0-1.5:1.7-2.3:0.1-1.0, and the value of x is determined by the oxidation state of each element; Ni is introduced by nickel molybdate, Mo is introduced by a molybdate and the nickel molybdate, and the nickel molybdate is prepared by co-precipitation of a molybdate and a nickel salt in the presence of an organic acid. According to the application, the content of different valence metals on the surface of the catalyst can be adjusted by introducing nickel into the catalyst through nickel molybdate, so that the content of high-valence elements Mo 6+ , V 5+ and Ni 2+ in the catalyst and the oxygen vacancy are increased, and the redox capacity of the catalyst is enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a catalyst for catalytically synthesizing acrylic acid from propane and application thereof. BACKGROUND

[0002] Acrylic acid is an important organic chemical raw material and oil field chemical additive. Driven by strong demand from four fields of building, textile, health and material, the market of acrylic ester in China is developing rapidly. China is the largest consumer and producer of acrylic acid in the world, and gradually develops towards scale, full industry chain and high-end. At present, acrylic acid is synthesized by a two-step method in industry, that is, propylene is first reacted with oxygen to generate propylene aldehyde, and then propylene aldehyde is oxidized to generate acrylic acid. While the global propylene production capacity is slowly increasing, the demand for propylene is rapidly increasing, and the gap is continuously increasing.

[0003] In the 21st century, the petroleum chemical raw materials will possibly shift to natural gas-based alkanes, so the shift of raw material route from olefins to alkanes will be one of the focuses of research and development of petroleum chemical technology in the new century. Low-carbon alkanes exist widely in the world, and their chemical conversion into high-value chemical products can bring huge economic benefits. The chemical conversion of low-carbon alkanes all faces similar difficulties: the raw materials are stable and cheap, but the conversion is difficult, and the target products are relatively active and easy to be further deeply oxidized. Therefore, it is difficult to simultaneously obtain high conversion rate and selectivity for the target products of the chemical conversion of low-carbon alkanes, and the two may exist in a seesaw relationship. So far, only a few reactions have realized industrial production, such as steam cracking of ethane to produce ethylene, dehydrogenation of propane to produce propylene, and selective oxidation of butane to produce maleic anhydride. The alkane activation technologies that may be industrialized in the 21st century include production of acetic acid from ethane, production of methacrylic acid from isobutane, catalytic dehydrogenation of ethane to produce ethylene, and production of acrylic acid from propane, etc.

[0004] Propane is one of the important components of natural gas, liquefied petroleum gas and coal bed gas. China is a country with relatively rich propane resources, such as propane accounting for about 6% in oil field gas, about 60% in liquefied petroleum gas, up to 15% in wet natural gas, and a certain amount of propane in refinery gas. A latest research of the World Energy Institute (WRI) shows that the shale gas reserves in China are as high as 30 trillion cubic meters, ranking first in the world, almost twice as much as that in the United States. With the accelerated exploitation of unconventional oil and gas such as shale gas, the potential supply of propane is relatively large. They are generally used as fuel or vented and burned, and the resource waste is large. How to convert this part of low-carbon alkanes into high-value chemical products to reduce the dependence on oil not only has huge economic benefits, but also has potential social benefits of delaying the depletion of oil. Therefore, it is of great significance to carry out researches on oxidation dehydrogenation to produce propylene, selective oxidation to produce propylene aldehyde, acrylic acid, isopropyl alcohol and acetone, dehydrogenation aromatization, and ammoxidation to produce acrylonitrile, etc.

[0005] Propane selective oxidation to acrylic acid is a complex integrated system process, and catalyst development is the core technology of the reaction process. In addition, reactor selection and design, reaction condition control, product separation, etc. are the main research topics. So far, there are three kinds of catalyst systems in the process of propane selective oxidation to acrylic acid: (1) industrial n-butane selective oxidation to maleic anhydride catalyst: VPO catalyst; (2) alkane oxidative dehydrogenation catalyst: heteropoly acid and its salt catalyst HxCs3-xPMo12O40(x=0~3) (HPC); (3) propane ammoxidation and alkane oxidative dehydrogenation catalyst: composite metal oxide (MMO) catalyst. The research on propane selective oxidation to acrylic acid catalyst is mostly derived from these three kinds of catalyst systems.

[0006] VPO catalyst is a very successful catalyst developed in the 1970s for preparing maleic anhydride from n-butane oxidation. In 1986, VPO catalyst was first used for propane selective oxidation, and the product was acrylic acid and carbon oxide, but the yield of acrylic acid was very low. Cheng Hua et al. added 0.01% Ce to the VPO catalyst to obtain 18.8% acrylic acid yield and 68% selectivity, which is a relatively high acrylic acid yield. There are reports that microwave heating method can be used to prepare VPO catalyst containing Ce and La. The results show that when the composition of the catalyst is n(P):n(V):n(La):n(Ce)=1.1:1.0:0.04:0.04, it has the highest propane conversion rate and acrylic acid selectivity, reaching 50.3% and 85.5% respectively. Through X-ray diffraction and laser Raman spectrum analysis, it is considered that the synergistic effect between CeP5O 14 and (VO)2P2O7 two phases can maintain the stability of the catalyst and improve the propane conversion rate and the selectivity of acrylic acid. Although this is the best VPO catalyst for acrylic acid selectivity and yield so far, the reaction temperature of this catalyst is relatively high, at 450℃. From the existing research results, there is no breakthrough in the preparation of VPO catalyst for acrylic acid, and it is far from reaching the requirements of industrial production.

[0007] HPC has its own advantages as a catalyst for propane selective oxidation to acrylic acid. Its structure is determined and the composition is simple. As a catalyst, HPC has both acidity and redox properties, and is a bifunctional catalyst. However, the stability of this type of catalyst is poor, and the activity decreases rapidly. Because the Keggin anion of heteropoly acid catalysts decomposes at 400℃ in air atmosphere. Therefore, for HPC for propane selective oxidation, improving its thermal stability is the key. H x Cu 0.6 Cr 0.6 PMo 10 V2As 0.6 O40 The catalyst achieved the highest yield of acrylic acid (14.8%) on HPCs system so far, and HPC has not achieved a breakthrough in propane selective oxidation to acrylic acid.

[0008] The composite metal oxide catalyst for propane selective oxidation is mainly a transition metal oxide catalyst. Compared with VPO and HPC catalysts, the structure and performance relationship of MMO catalysts is more complex. Because it is calcined at high temperature in the preparation process, it has good thermal stability. The catalysts for the oxidation of propylene to propylene aldehyde and acrylic acid used in industry also belong to this system. In recent years, it has been found that composite metal oxides have good catalytic effect on the reaction of propane selective oxidation to acrylic acid, and have been paid attention to and become a research hotspot. At present, most of the composite metal oxides for propane oxidation 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. The most studied are Mo-V-Te-Nb and Mo-V-Sb-Nb catalysts. Although these catalysts have complex preparation process, a variety of by-products, and their stability and reproducibility need to be improved, they have higher catalytic activity than VPO and HPA catalysts, higher reaction activity and selectivity of target product, higher thermal stability, active components are not easy to lose, and are not easy to produce carbon deposition at low and high temperatures, etc., which makes them more suitable for use as catalysts for propane selective oxidation to acrylic acid. Among the several major catalyst systems for propane selective oxidation to acrylic acid, the Mo-V-Te-Nb catalyst system has higher reaction activity and selectivity of target product, and is the best catalyst system for propane selective oxidation to acrylic acid at present. Many researchers have conducted in-depth research on the preparation method and conditions of the catalyst, the bulk and surface crystal structure of the catalyst, and the catalytic kinetics. At present, there is no report on the industrial application of propane oxidation to acrylic acid at home and abroad, and it still remains in the laboratory research stage.

[0009] Ushikubo et al. first discovered in 1997 that the Mo-V-Te-Nb-O catalyst system had extremely high activity and selectivity for the selective oxidation of propane to acrylonitrile, and the highest yield of acrylonitrile reached nearly 50%. The Mo-V-Te-Nb-O catalyst developed by Mitsubishi Company in Japan is the best composite metal oxide catalyst reported so far, and the yield of acrylic acid obtained is 48%. However, the Mo-V-Te-Nb-O catalysts prepared by different researchers have different properties. 0.3 Te 0.23 Nb 0.l2 O x 0.3 Te 0.23 Nb 0.l2 O x ​The catalysts have a large difference in acrylic acid yield. This can be due to the multiple elements of the catalyst composition and the complex preparation procedure. Therefore, strict control of the catalyst preparation conditions is the key to obtaining ideal acrylic acid.

[0010] Patent No. CN1596244A reports a method for producing acrylic acid from propane in the absence of molecular oxygen. The method uses a gas mixture containing propane, steam, and an inert gas in the absence of molecular oxygen and passes through the catalyst reported in the patent. The use of this method reduces the high content of by-product propionic acid in the previous propane-to-acrylic acid process, significantly reduces the propionic acid / acrylic acid ratio at the reactor outlet, and reduces the content of by-product acetone. However, the yield of acrylic acid is only 10.5%.

[0011] Patent No. CN1326378A reports a Mo-V-Ga-Pd-Nb-X (where X = La, Te, etc.) catalytic system for propane low-temperature partial oxidation with a molecular oxygen-containing gas. The catalyst produces acrylic acid at low temperatures through the gas-phase partial oxidation of propane. At a temperature of 200-300°C, a pressure of atmospheric pressure, and a reaction space velocity of 200-3000 LKg -1 h -1 , the propane conversion rate is 10%-25%, and the acrylic acid selectivity is 20%-45%.

[0012] Patent No. CN102179261A reports the preparation of acrylic acid by catalyzing propane oxidation with Mo, V, Te, and Nb as active components. The patent provides a template synthesis method for preparing propane selective oxidation to acrylic acid composite metal oxide catalysts with periodic regular ordered structures, solving the problems of large particle size and uneven structure in the previous catalyst preparation process. The highest propane conversion rate is 68.3%, and the acrylic acid yield is about 45%, but the template synthesis method results in high preparation cost.

[0013] Patent CN114534750A discloses a preparation method of a propane selective oxidation catalyst for preparing acrylic acid. By fixing the molar ratio of Mo-V-Te-Nb active components and adding NiSb2O6 as an additive to the Mo-V-Te-Nb active components, the activity, selectivity, and stability of the catalyst are effectively improved. The introduction of NiSb2O6 structure helps to reduce the total acid amount on the catalyst surface. In this method, NiSb2O6 needs to be calcined at a high temperature of 800°C or higher, then mixed with Mo-V-Te-Nb active components, and then granulated, shaped, dried, and calcined to obtain the catalyst. Therefore, the catalyst needs to be calcined twice during preparation, resulting in a long preparation process and high production cost. SUMMARY

[0014] The application aims to provide a catalyst for catalytic synthesis of propylene acid from propane, so as to solve the problems of low propane conversion activity, serious oxidation of target product, poor stability of catalyst or long preparation process in the prior art, and further develop the application value of Mo-V system composite metal oxide catalyst in industry.

[0015] The application also aims to provide an application of the catalyst for catalytic synthesis of propylene acid from propane in a fixed bed reactor.

[0016] To achieve the above-mentioned purposes, the application provides a catalyst for catalytic synthesis of propylene acid from propane, which is represented by the following general formula:

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

[0018] wherein a, b, c, d and e respectively represent the atomic numbers of Mo, V, Te, Nb and Ni, and a:b:c:d:e is 7.0-9.0:1.7-2.5:1.0-1.5:1.7-2.3:0.1-1.0 in terms of molar ratio, and the value of x is determined by the oxidation state of each element; Ni is introduced through nickel molybdate, Mo is introduced through molybdate and the nickel molybdate, which is prepared by co-precipitation of molybdate and nickel salt in the presence of organic acid.

[0019] The catalyst for catalytic synthesis of propylene acid from propane is prepared by the following method: 1) dissolving and uniformly mixing molybdate, vanadate, tellurium compound and niobium salt, co-precipitating to form a slurry, and then drying and crushing to prepare Mo-V-Te-Nb active component; 2) uniformly mixing organic acid, nickel salt, molybdate and deionized water, and then drying and crushing to obtain nickel molybdate component; 3) mixing Mo-V-Te-Nb and nickel molybdate, dry mixing the materials, adding a binder to form a paste, and then granulating, molding, drying and calcining to obtain the catalyst.

[0020] The catalyst for catalytic synthesis of propylene acid from propane has a calcination temperature greater than or equal to 600 DEG C in step 3).

[0021] The catalyst for catalytic synthesis of propylene acid from propane has that the organic acid, nickel source, molybdenum source and deionized water are mixed in step 2) at a pH of 2-5.

[0022] The catalyst for synthesizing acrylic acid from propane catalytically in the application, in the 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 / or diatomic tellurium, and the niobium salt is one of niobium oxalate, niobium acetate and ammonium niobium oxalate; in the 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.

[0023] The catalyst for synthesizing acrylic acid from propane catalytically in the application, in the step 3), the binder is one or several of silica sol, aluminum sol and silica-aluminum sol, and the binder is preferably silica sol.

[0024] To achieve the above-mentioned purpose, the application also provides an application of the above-mentioned catalyst in a fixed bed reactor, and the catalyst is filled in the reactor in a way that the concentration of the catalyst gradually increases from the inlet to the outlet of the reactor.

[0025] The application of the catalyst in a fixed bed reactor in the application, and the heating medium of the fixed bed reactor is a molten salt composed of potassium nitrate, sodium nitrate and sodium nitrite, and the temperature of the molten salt is 380 DEG C to 420 DEG C.

[0026] The application of the catalyst in a fixed bed reactor in the application, and during the reaction, the total mass space velocity is 2000 ml / (g.h) to 3500 ml / (g.h), the volume ratio of oxygen to propane is 1.5 to 5, the volume ratio of water to propane is 1 to 10, and the rest is nitrogen.

[0027] The application of the catalyst in a fixed bed reactor in the application, and the propane is 5 vol% to 15 vol% of the total gas amount.

[0028] The application has the following beneficial effects:

[0029] The catalyst in the application uses self-made nickel molybdate as an auxiliary active component, and nickel is introduced into the catalyst through the nickel molybdate. The nickel molybdate is prepared by co-precipitation of a molybdate and a nickel salt in the presence of an organic acid, and the carboxyl group in the organic acid supports the function of the local environment, can disperse the crystal lattice clusters, makes the nickel molybdate oxide "fine crystallization", realizes the full exposure of the molybdenum, vanadium and nickel components, and makes the high-valence elements Mo 6+ 、V 5+ and Ni 2+The content and oxygen vacancy content increase, the redox ability of the catalyst is enhanced, under the process condition that the propane is 5vol% to 15vol% of the total gas amount, the propane conversion activity is maintained at a high level. Moreover, the catalyst is filled in a manner that the catalyst concentration gradually increases from the inlet to the outlet of the reactor, which is beneficial to inhibit the deep oxidation of the product and further improve the selectivity. In addition, the nickel molybdate does not need to be calcined at high temperature, and after low-temperature drying, the catalyst can be prepared by mixing with the Mo-V-Te-Nb-B component, and the preparation process is simplified. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 H2-TPR characterization chart of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0031] The application will be described in detail below by examples. It is necessary to point out here that the following examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application, and those skilled in the art can make some non-essential improvements and adjustments to the application according to the above content of the application.

[0032] Example 1

[0033] Preparation of Catalyst 1

[0034] First step: preparation of catalyst slurry 1-1 of the application by dissolution-co-precipitation method

[0035] In the No. 1 beaker, 158.7g of ammonium heptamolybdate, 28.8g of ammonium metavanadate, 49.8g of telluric acid and 200ml of water were added, and the mixture was stirred at 75-80℃ to dissolve. In the No. 2 beaker, 179.2g of niobium oxalate and 200ml of distilled water were added and stirred at 75-80℃ to dissolve, and then the solution in the No. 2 beaker was slowly added dropwise into the No. 1 beaker, and a multi-component composite metal oxide catalyst slurry 1-1 was prepared by normal pressure reaction for 2h;

[0036] Second step: preparation of nickel molybdate component 1-2

[0037] In the No. 3 beaker, 9g of oxalic acid, 17.9g of ammonium heptamolybdate and 50ml of deionized water were mixed uniformly in a 200ml beaker; in the No. 4 beaker, 4.21g of nickel nitrate was dissolved in 10ml of deionized water; then the solution in the No. 4 beaker was added dropwise into the No. 3 beaker, and the PH value of the solution was adjusted to 2 with ammonia water, and after mixing, the slurry was reacted at 55-60℃ under normal pressure for 2.5h to obtain a slurry containing nickel molybdate; the slurry 1-2 was first dried at 80℃ in an oven for 16h, and then dried at 120℃ for 1.5h, and then ground and crushed to form 50-100 mesh particles, which were the nickel molybdate component 1-2;

[0038] Third step: preparation of catalyst

[0039] After drying the slurry 1-1, crushing, grinding, and making the bulk into 50-100 mesh active component granules 1-3, the active component granules 1-3 are uniformly mixed with 1-2, and added to a kneading device, dry mixed for 1.0 h, then silica sol is added to the mixture, the amount of silica sol added is 10% of the mass of the above-mentioned solid powder, kneaded to form a paste, granulated, shaped, and made into mesoporous granules with an inner diameter of 1.5 mm, an outer diameter of 4.5 mm, and a height of 4.5 mm, dried, calcined at 200°C in an air atmosphere for 3 h, calcined at 600°C in a nitrogen atmosphere for 2 hours to obtain catalyst 1, the molar ratio of Mo, V, Te, Nb, and Ni is 7.0:1.7:1.5:2.3:0.1.

[0040] Fourth step: performance test of catalyst 1

[0041] The fixed bed reactor has an inner diameter of 25 mm, is provided with a thermocouple, and is sequentially filled with catalyst F2 segment and F1 segment along the raw material gas inlet direction of the reaction tube, the F2 segment is 50 ml of the catalyst prepared in the fifth step, and the F1 segment is a uniform mixture of 50 ml of the catalyst prepared in the fifth step and 50 ml of φ4.5 inert porcelain balls. The heating medium is a molten salt composed of potassium nitrate, sodium nitrate, and sodium nitrite, and the salt bath heating temperature is controlled at 390°C. The reaction raw materials propane, oxygen, and nitrogen are mixed by a gas cylinder, a pressure reducing valve, and a preheater into a mixer, a trace amount of water is injected into a vaporizer by a micro pump, and after vaporization at 200°C, it is mixed with propane, nitrogen, and oxygen in the mixer and then enters the reactor. The concentration of propane in the raw material gas is 7 vol%, the raw material gas space velocity GSHV is 2800 ml / (g·h), the oxygen / propane (vol%) is 4, the water / propane (vol%) is 6, and the rest is nitrogen, and the reaction pressure is 25 KPa. The experimental results are shown in Table 2, which shows that the use of catalyst 1 in the reaction process is stable, the performance is stable, and the long-period stable operation of the propane selective oxidation reaction can be realized.

[0042] Example 2

[0043] Preparation of catalyst 2

[0044] First step: preparation of the catalyst slurry 1-1 of the application by dissolution-co-precipitation method

[0045] In a No. 1 beaker, 141.5 g of ammonium heptamolybdate, 24.8 g of ammonium metavanadate, 25.5 g of telluric acid, and 100 ml of water are added, and the mixture is stirred at 75-80°C to dissolve it. In a No. 2 beaker, 107.6 g of niobium oxalate and 100 ml of distilled water are added and stirred at 75-80°C to dissolve it. Then the solution in the No. 2 beaker is slowly added to the No. 1 beaker, and a normal pressure reaction is carried out for 2 h to obtain a slurry 1-1 of a multi-component composite metal oxide catalyst;

[0046] Second step: preparation of nickel molybdate component 1-2

[0047] In No. 3 beaker, 15 g of citric acid, 47.4 g of ammonium heptamolybdate and 100 ml of deionized water were mixed evenly in a 500 ml beaker; in No. 4 beaker, 17.1 g of nickel nitrate and 20 ml of deionized water were mixed evenly; then the solution in No. 4 beaker was added dropwise into No. 3 beaker, and the pH value of the solution was adjusted to 2 with ammonia water; after mixing, the slurry containing nickel molybdate was obtained by reacting at 55-60 °C under normal pressure for 2.5 h; the slurry 1-2 was first dried at 80 °C for 16 h, and then dried at 120 °C for 1.5 h; after crushing and grinding, 50-100 mesh particles were formed, which were nickel molybdate component 1-2;

[0048] Third step: preparation of catalyst

[0049] After drying the slurry 1-1, crushing and grinding were performed to form 50-100 mesh active component particles 1-3; the active component particles 1-3 and 1-2 were uniformly mixed and added to a kneading device; after dry mixing for 1.0 h, silica sol was added to the mixture, and the amount of silica sol added was 10% of the mass of the above-mentioned solid powder; the mixture was kneaded to form a paste, and then granulated and shaped to form mesoporous particles with an inner diameter of 1.5 mm, an outer diameter of 4.5 mm and a height of 4.5 mm; after drying, the catalyst 1 was obtained by calcining at 200 °C in air for 3 h and at 600 °C in nitrogen for 2 h, and the molar ratio of Mo, V, Te, Nb and Ni was 9.0:1.8:0.9:1.7:0.5.

[0050] The performance test of catalyst 2 was the same as that of catalyst 1. The experimental results are shown in Table 2.

[0051] Example 3

[0052] Preparation of catalyst 3

[0053] First step: preparation of catalyst slurry 1-1 by dissolution-co-precipitation method

[0054] In No. 1 beaker, 154.5 g of ammonium heptamolybdate, 40.7 g of vanadyl oxalate, 28.7 g of telluric acid and 100 ml of water were added and stirred at 75-80 °C to dissolve; in No. 2 beaker, 134.5 g of niobium oxalate and 100 ml of distilled water were added and stirred at 75-80 °C to dissolve; then the solution in No. 2 beaker was slowly added dropwise into No. 1 beaker, and the slurry 1-1 containing multi-component composite metal oxide catalyst was prepared by reacting under normal pressure for 2 h;

[0055] Second step: preparation of nickel molybdate component 1-2

[0056] In No. 3 beaker, 18 g of oxalic acid, 22.1 g of ammonium heptamolybdate and 200 ml of deionized water were mixed in a 500 ml beaker; in No. 4 beaker, 36.4 g of nickel nitrate and 50 ml of deionized water were mixed; then the solution in No. 4 beaker was added dropwise into No. 3 beaker, and the pH value of the solution was adjusted to 5 with ammonia water, and after mixing, the slurry was reacted at 55-60 °C under normal pressure for 2.5 h to obtain a slurry containing nickel molybdate; the slurry was first dried at 80 °C in an oven for 16 h, and then dried at 120 °C for 1.5 h, and after grinding and crushing, 50-100 mesh particles were formed, which were the nickel molybdate component 1-2;

[0057] Third step: preparation of the catalyst

[0058] After drying the slurry 1-1, the blocky material was broken and ground to form 50-100 mesh active component particles 1-3, which were uniformly mixed with 1-2, and then added to a kneading device, and after dry mixing for 1.0 h, silica sol was added to the mixture, and the amount of silica sol added was 10% of the mass of the above-mentioned solid powder, and the mixture was kneaded to form a paste, and then granulated and shaped to form mesoporous particles with an inner diameter of 1.5 mm, an outer diameter of 4.5 mm and a height of 4.5 mm, and after drying, the particles were calcined in air at 200 °C for 3 h and in nitrogen at 600 °C for 2 h to obtain catalyst 1, which had a molar ratio of Mo, V, Te, Nb and Ni of 8.0:2.1:1.0:2.0:1.0.

[0059] The performance of catalyst 3 was tested in the same way as catalyst 1. The experimental results are shown in Table 2.

[0060] Example 4

[0061] Preparation of catalyst 4

[0062] First step: preparation of the catalyst slurry 1-1 of the present application by dissolution-co-precipitation method

[0063] In No. 1 beaker, 135.0 g of ammonium heptamolybdate, 55.8 g of vanadyl oxalate, 32.8 g of telluric acid and 100 ml of water were added, and the mixture was stirred at 75-80 °C to dissolve; in No. 2 beaker, 153.9 g of niobium oxalate and 100 ml of distilled water were added, and the mixture was stirred at 75-80 °C to dissolve; then the solution in No. 2 beaker was slowly added dropwise into No. 1 beaker, and the reaction was carried out under normal pressure for 2 h to obtain a slurry containing a plurality of components of composite metal oxide catalyst 1-1;

[0064] Second step: preparation of the nickel molybdate component 1-2

[0065] In a 3rd beaker, 18 g of citric acid, 22.0 g of ammonium tetramolybdate and 200 ml of deionized water were mixed in a 500 ml beaker; in a 4th beaker, 20.6 g of nickel nitrate and 50 ml of deionized water were mixed; then the solution in the 4th beaker was added dropwise into the 3rd beaker, and the pH value of the solution was adjusted to 4 with ammonia water, and after mixing, the slurry containing nickel molybdate was obtained by reacting at 55-60°C under normal pressure for 2.5 h; the slurry was first dried at 80°C in an oven for 16 h, and then dried at 120°C for 1.5 h, and after grinding and crushing, 50-100 mesh particles were formed, which were the nickel molybdate component 1-2;

[0066] Third step: preparation of the catalyst

[0067] After drying the slurry 1-1, the blocky material was broken and ground to form 50-100 mesh active component particles 1-3, which were uniformly mixed with 1-2, and then added to a kneading device, and after dry mixing for 1.0 h, silica sol was added to the mixture, and the amount of silica sol added was 10% of the mass of the above-mentioned solid powder, and the mixture was kneaded to form a paste, and then granulated and shaped to form mesoporous particles with an inner diameter of 1.5 mm, an outer diameter of 4.5 mm and a height of 4.5 mm, and after drying, the catalyst 1 was prepared by calcining at 200°C in air for 3 h and at 600°C in nitrogen for 2 h, and the molar ratio of Mo, V, Te, Nb and Ni was 7.0:2.5:1.0:2.0:0.5. The performance test of catalyst 4 was the same as that of catalyst 1. The experimental results are shown in Table 2.

[0068] Example 5

[0069] Preparation of catalyst 5

[0070] First step: preparation of the catalyst slurry 1-1 of the present application by dissolution-co-precipitation method

[0071] In a 1st beaker, 145.2 g of ammonium tetramolybdate, 26.3 g of ammonium metavanadate, 37.3 g of telluric acid and 100 ml of water were added, and the mixture was stirred at 75-80°C to dissolve, and in a 2nd beaker, 114.3 g of niobium oxalate and 100 ml of distilled water were added, and the mixture was stirred at 75-80°C to dissolve, and then the solution in the 2nd beaker was slowly added dropwise into the 1st beaker, and the slurry containing multi-component composite metal oxide catalyst 1-1 was prepared by reacting under normal pressure for 2 h;

[0072] Second step: preparation of the nickel molybdate component 1-2

[0073] In No. 3 beaker, 12 g of oxalic acid, 11.8 g of ammonium tetramolybdate and 100 ml of deionized water were mixed uniformly in a 200 ml beaker; in No. 4 beaker, 4.4 g of nickel acetate and 50 ml of deionized water were mixed uniformly; then the solution in No. 4 beaker was added dropwise into No. 3 beaker, and the pH value of the solution was adjusted to 3 with ammonia water, and after mixing, the slurry containing nickel molybdate was reacted at 55-60°C under normal pressure for 2.5 h; the slurry was first dried at a constant temperature of 80°C for 16 h, and then dried at 120°C for 1.5 h, and after grinding and crushing, 50-100 mesh granules were formed, which were the nickel molybdate component 1-2.

[0074] Step 3: Preparation of the catalyst

[0075] After drying the slurry 1-1, the block-shaped material was broken and ground to form 50-100 mesh active component granules 1-3, which were uniformly mixed with 1-2, and then added into a kneading device, and after dry mixing for 1.0 h, silica sol was added into the mixture, and the amount of silica sol was 10% of the mass of the above-mentioned solid powder, and the mixture was kneaded to form a paste, and then granulated and shaped to form mesoporous granules with an inner diameter of 1.5 mm, an outer diameter of 4.5 mm and a height of 4.5 mm, and after drying, the catalyst 1 was prepared by calcining at 200°C in air for 3 h and at 600°C in nitrogen for 2 h, and the molar ratio of Mo, V, Te, Nb and Ni was 8.0:1.8:1.3:1.7:0.2.

[0076] The performance test of catalyst 5 was the same as that of catalyst 1. The experimental results are shown in Table 2.

[0077] Example 6

[0078] The catalyst in the third step of Example 1 was shaped into mesoporous granules with an inner diameter of 1.0 mm, an outer diameter of 3 mm and a height of 3 mm, and the oxidation reaction conditions were the same as those of Example 1. The experimental results are shown in Table 2.

[0079] Example 7

[0080] The catalyst in the third step of Example 1 was shaped into mesoporous granules with an inner diameter of 1.8 mm, an outer diameter of 5.5 mm and a height of 5.5 mm, and the oxidation reaction conditions were the same as those of Example 1. The experimental results are shown in Table 2.

[0081] Example 8

[0082] The catalyst in the third step of Example 1 was shaped into spherical granules with a diameter of 4.5 mm, and the oxidation reaction conditions were the same as those of Example 1. The experimental results are shown in Table 2.

[0083] Example 9

[0084] The catalyst is the same as that in Example 1, and the performance test conditions are as follows: the space velocity of the raw gas GSHV = 3500 ml / (g-h), the concentration of propane in the raw gas is 7 vol%, the oxygen / propane (vol%) = 4, the water / propane (vol%) = 6, and the rest is nitrogen. The experimental results are shown in Table 2.

[0085] Example 10

[0086] The catalyst is the same as that in Example 1, and the performance test conditions are as follows: the space velocity of the raw gas GSHV = 3500 ml / (g-h), the concentration of propane in the raw gas is 10 vol%, the oxygen / propane (vol%) = 4, the water / propane (vol%) = 6, and the rest is nitrogen. The experimental results are shown in Table 2.

[0087] Example 11

[0088] The catalyst is the same as that in Example 1, and the performance test conditions are as follows: the space velocity of the raw gas GSHV = 2800 ml / (g-h), the concentration of propane in the raw gas is 12 vol%, the oxygen / propane (vol%) = 2, the water / propane (vol%) = 4, and the rest is nitrogen. The experimental results are shown in Table 2.

[0089] Example 12

[0090] The catalyst is the same as that in Example 1, and the performance test conditions are as follows:

[0091] The fixed bed reactor has an inner diameter of 25 mm and is provided with a thermocouple. The catalyst F3, F2 section and F1 section are sequentially filled along the raw gas inlet direction of the reaction tube. The F3 section is the catalyst prepared in the fifth step, 50 ml; the F2 section is a uniform mixture of the catalyst prepared in the fifth step, 30 ml, and 20 ml of φ4.5 inert porcelain balls; and the F1 section is a uniform mixture of the catalyst prepared in the fifth step, 20 ml, and 30 ml of φ4.5 inert porcelain balls. The temperature of the salt bath heating is controlled at 390°C. The raw propane, oxygen and nitrogen are mixed in a mixer after passing through a pressure reducing valve and a preheater from a gas cylinder. A small amount of water is injected into a vaporizer by a micro-flow pump, vaporized at 200°C, and then mixed with propane, nitrogen and oxygen in the mixer before entering the reactor. The concentration of propane in the raw gas is 15 vol%, the space velocity of the raw gas GSHV = 2800 ml / (g-h), the oxygen / propane (vol%) = 4, the water / propane (vol%) = 6, and the rest is nitrogen. The reaction pressure is 25 KPa. The experimental results are shown in Table 2.

[0092] Example 13

[0093] The catalyst in the third step of Example 5 is changed from being calcined at 200°C in air for 3 h and then at 600°C in nitrogen for 2 h to being calcined at 600°C in nitrogen for 2 h.

[0094] The performance test is the same as that of Catalyst 1, and the experimental results are shown in Table 2.

[0095] Example 14

[0096] The calcination of the catalyst in the third step of Example 5 is changed to 200°C air atmosphere for 3h and 600°C nitrogen atmosphere for 2h.

[0097] The performance test is the same as Example 1, and the experimental results are shown in Table 2.

[0098] Example 15

[0099] The catalyst is the same as Example 1, and the performance test conditions are:

[0100] The fixed bed reactor has an inner diameter of 25mm, and a thermocouple is arranged inside. 50ml of the catalyst prepared in the third step is loaded along the raw material gas inlet direction of the reaction tube. The salt bath heating temperature is controlled at 390°C. Propane, oxygen and nitrogen from gas cylinders pass through pressure reducing valves and preheaters into a mixer, and a trace amount of water is injected into a vaporizer by a micro pump, and after vaporization at 200°C, it is mixed with propane, nitrogen and oxygen in the mixer and then enters the reactor. The propane concentration in the raw material gas is 7vol%, the raw material gas space velocity GSHV is 2800ml / (g.h), the oxygen / propane (vol%) is 4, the water / propane (vol%) is 6, and the rest is nitrogen. The reaction pressure is 25KPa, and the experimental results are shown in Table 2.

[0101] Comparative Example D1

[0102] The same as Example 1, except that in the first step, the catalyst slurry 1-1 of the present application is prepared by the dissolution-co-precipitation method

[0103] In a No. 1 beaker, 176.6g of ammonium heptamolybdate, 28.4g of ammonium metavanadate, 49.1g of telluric acid and 200ml of water are added, and the mixture is stirred at 75-80°C to dissolve. In a No. 2 beaker, 177.0g of niobium oxalate, 4.2g of nickel nitrate and 100ml of distilled water are added and stirred at 75-80°C to dissolve. Then, the solution in the No. 2 beaker is slowly added dropwise to the No. 1 beaker, and a multi-component composite metal oxide catalyst slurry 1-1 is prepared by atmospheric reaction for 2h. The slurry 1-1 is dried and then crushed and ground to form active component granules of 50-100 mesh. The other steps are the same as Example 1, and a catalyst with a Mo:V:Te:Nb:Ni ratio of 7.0:1.7:1.5:2.3:0.1 is prepared.

[0104] The catalyst performance is evaluated according to the catalyst performance test method of Example 1, and the experimental results are shown in Table 2.

[0105] The catalysts obtained in Example 1 and Comparative Example D1 are subjected to H2-TPR detection and XPS characterization, and the results are shown in Table 1 and Table 2. From the results of H2-TPR detection and XPS characterization, it can be seen that the catalyst of the present application has a higher reduction temperature and a higher content of active components, and the catalyst has a higher catalytic activity. Figure 1 and Table 1. From the results of H2-TPR detection and XPS characterization, it can be seen that the catalyst of the present application has a higher reduction temperature and a higher content of active components, and the catalyst has a higher catalytic activity.Figure 1 It can be seen that, compared with the introduction of nickel source in the form of nickel nitrate, the introduction of nickel source in the form of nickel molybdate makes the hydrogen consumption significantly increase, and the number of surface reducible species on the surface of the catalyst significantly increases. In combination with the XPS characterization results in Table 1, the reason for the significant increase in the reduction peak area is that the introduction of nickel molybdate adjusts the element valence state ratio of the catalyst, and the contents of elements Mo 6+ , V 5+ and Ni 2+ in high valence state and oxygen vacancies increase. Therefore, the number of reducible species increases, the redox ability of the catalyst is enhanced, and thus the reaction activity of the catalyst is improved.

[0106] Table 1

[0107]

[0108] Comparative Example D2

[0109] First step: preparation of catalyst slurry 1-1 of the application by dissolution-co-precipitation method

[0110] In a beaker No. 1, 176.6 g of ammonium heptamolybdate, 28.4 g of ammonium metavanadate, 49.1 g of telluric acid and 100 ml of water were added, and the mixture was stirred at 75-80°C to dissolve. In a beaker No. 2, 176.5 g of niobium oxalate and 100 ml of distilled water were added, and the mixture was stirred at 75-80°C to dissolve. Then, the solution in the beaker No. 2 was slowly added dropwise into the beaker No. 1, and a multi-component composite metal oxide catalyst slurry 1-1 was prepared by normal pressure reaction for 2 h. The slurry 1-1 was dried, and then crushed and ground to form 50-100 mesh active component particles. The other steps were the same as in Example 1, and a catalyst with Mo:V:Te:Nb of 7.0:1.7:1.5:2.3 was prepared.

[0111] According to the catalyst performance test method of Example 1, the catalytic performance was evaluated, and the experimental results are shown in Table 2.

[0112] Comparative Example D3

[0113] The first step was the same as in Example 2;

[0114] The second step was to use commercially available nickel molybdate (manufacturer: Alfa, item number: 089938, purity: 98%).

[0115] The 10.4 g of nickel molybdate is mixed with the active component particles 1-3 prepared in the first step, and then added into a kneading device. After dry mixing for 1.0 h, silica sol is added into the mixture, the amount of silica sol added is 10% of the mass of the solid powder, and then kneaded into a paste, granulated and shaped into mesoporous particles with an inner diameter of 1.5 mm, an outer diameter of 4.5 mm and a height of 4.5 mm. After drying, the catalyst 1 is obtained by calcining at 200 °C in air for 3 h and at 600 °C in nitrogen for 2 h, and the molar ratio of Mo, V, Te, Nb and Ni is 9:2.2:1.2:2.1:0.5.

[0116] The catalyst performance is evaluated according to the catalyst performance test method of Example 1, and the experimental results are shown in Table 2.

[0117] Table 2

[0118]

[0119]

[0120] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A catalyst for the catalytic synthesis of propene acid from propane, characterized in that, The catalyst is represented by the following general formula: Mo a V b Te c Nb d Ni e O x In the formula, a, b, c, d, and e represent the atomic numbers of Mo, V, Te, Nb, and Ni, respectively, and a:b:c:d:e is 7.0-9.0:1.7-2.5:1.0-1.5:1.7-2.3:0.1-1.0 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, and Mo is introduced by a molybdate and the nickel molybdate, which is prepared by co-precipitation of a molybdate and a nickel salt in the presence of an organic acid.

2. The catalyst according to claim 1, characterized in that, The catalyst is prepared by the following method: 1) dissolving and uniformly mixing a molybdate, a vanadate, a tellurium compound, and a niobium salt, co-precipitating to form a slurry, and then drying and crushing to prepare a Mo-V-Te-Nb active component; 2) uniformly mixing an organic acid, a nickel salt, a molybdate, and deionized water, and then drying and crushing to obtain a nickel molybdate component; and 3) mixing the Mo-V-Te-Nb and the nickel molybdate, dry mixing the materials, adding a binder to form a paste, and then granulating, molding, drying, and calcining to obtain the catalyst.

3. The catalyst of claim 2, wherein The calcination temperature in step 3) is greater than or equal to 600°C.

4. The catalyst of claim 2, wherein The organic acid, the nickel source, the molybdenum source, and the deionized water in step 2) are mixed at a pH of 2-5.

5. The catalyst of claim 2, wherein 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 telluric acid or diatomic tellurium, and the niobium salt is one of niobium oxalate, niobium acetate, and ammonium niobium oxalate; and 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 of claim 2, wherein The binder in step 3) is one or more of silica sol, aluminum sol, and silica-aluminum sol.

7. The catalyst of claim 2, wherein The binder in step 3) is silica sol.

8. Use of a catalyst according to any one of claims 1 to 7 for the catalytic synthesis of propene acid from propane, characterized in that, The catalyst is used in a fixed bed reactor, and the catalyst is loaded in a manner that the concentration of the catalyst gradually increases from the inlet to the outlet of the fixed bed reactor.

9. Use according to claim 8, characterized in that, The heating medium of the fixed bed reactor is a molten salt composed of potassium nitrate, sodium nitrate, and sodium nitrite, and the temperature of the molten salt is 380-420°C.

10. Use according to claim 8, characterized in that, During the reaction, the total mass space velocity is 2000-3500 ml / (g•h), the volume ratio of oxygen to propane is 1.5-5, the volume ratio of water to propane is 1-10, and the rest is nitrogen.

11. Use according to claim 10, characterized in that, The amount of propane is 5-15 vol% of the total gas.

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