Non-noble metal bi-component composite molecular sieve catalyst as well as preparation method and application thereof

Abstract

The invention discloses a non-noble metal bi-component composite molecular sieve catalyst as well as a preparation method and application thereof. The non-noble metal bi-component composite molecular sieve catalyst comprises a carrier and an active component loaded on the carrier, the active component comprises a first non-noble metal and a second non-noble metal; the first non-noble metal and the second non-noble metal are respectively and independently selected from one or more than two of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium, and the first non-noble metal and the second non-noble metal are different; the carrier is a silicon-based molecular sieve. A silicon-based molecular sieve is used as a carrier, a non-noble metal bi-component active center is introduced, rich silicon hydroxyl on the surface of the molecular sieve is used for grafting the metal center, a porous structure of the molecular sieve is used for promoting metal dispersion and stability, a first non-noble metal component automatically captures a second non-noble metal component, and an electronic modulation effect between the bi-metal components is generated; through reasonable regulation and control of the metal center load proportion and reasonable optimization of reaction conditions, alkane can be effectively, efficiently and economically converted into olefin, and hydrogen as a byproduct can be produced at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of alkane catalytic conversion, and more specifically, to a non-noble metal two-component composite molecular sieve catalyst and a preparation method and application thereof. Background Art

[0002] With the rapid development of the world economy, the demand for energy is increasing. However, with the development and utilization of fossil fuels, environmental problems are becoming increasingly prominent. Traditional fossil fuel resources such as coal, natural gas and oil are ultimately limited, and resource shortages are gradually becoming a common problem faced by countries around the world.

[0003] Shale gas resources are abundant, and its main components are methane, ethane, propane, etc. Shale gas is used as raw material to produce important chemical raw materials (such as ethylene, propylene, etc.), which has broad application prospects in the sustainable production of replacing traditional petroleum-based chemical raw materials. Propylene is the raw material for the production of industrial products such as acrolein, polypropylene, acetone, polyacrylonitrile, and propylene oxide, and can be further used to produce plastics, fibers, rubber, and fine chemicals. The annual demand maintains an average annual growth rate of 2% to 3%, and the demand is expected to reach 191 million tons by 2030. C4 olefins (i.e., butene, 1,3-butadiene, and isobutylene) are the main raw materials for the preparation of high-value-added downstream products such as polyethylene (LDPE), acrylonitrile butadiene styrene (ABS), polyisobutylene (PIB), methyl tert-butyl ether (MTBE), butyl rubber, and styrene butadiene rubber (SBR), and have a large market demand in the industrial production of rubber and polymer resins. The traditional production routes of propylene and C4 olefins are naphtha steam cracking (SC) and fluid catalytic cracking (FCC) of high-boiling oil. However, as the gap between supply and demand of low-carbon olefins continues to widen, several special technologies have been developed to increase olefin production, including propane dehydrogenation (PDH), methanol to propylene, Fischer-Tropsch process to olefins, butane dehydrogenation (BDH), isobutane dehydrogenation to isobutylene, etc. Among them, propane dehydrogenation technology is considered to be one of the most promising methods for propylene production, because it is a method for producing propylene exclusively, with only hydrogen as a by-product, and with the large amount of propane raw materials with reduced prices brought by the shale revolution, it provides a good opportunity for the directional catalytic dehydrogenation of propane to produce propylene, which currently accounts for about 10% of the global propylene production. At present, the main process technologies for direct dehydrogenation of propane to produce propylene include Catofin and Oleflex processes. The former is based on CrO x / Al2O3 material as catalyst, and the latter is PtSn / Al2O3 material as catalyst. The catalysts for butane dehydrogenation to butylene / butadiene and isobutane dehydrogenation to isobutene are also mainly metal oxide catalysts (CrOx-, VOx-, etc.) and noble metal catalysts (Pt-based). The two catalysts have their own disadvantages. Chromium-based catalysts are toxic, and the active center of platinum-based catalysts is the noble metal Pt, and the catalyst preparation cost is high. In addition, the reaction process is accompanied by the formation of carbon deposits, so the catalyst is easily deactivated. Air roasting regeneration is usually adopted. The regeneration process of platinum-based catalysts requires the injection of toxic chlorine to promote the redispersion of platinum, which is harmful to the environment and increases the risk of process operation. For the reaction of butane dehydrogenation to butadiene, Pt will cause serious dehydrogenation isomerization reaction of n-butane, which is not conducive to improving the selectivity of butadiene. Vanadium-based oxide catalysts will undergo isomerization reaction in the isobutane dehydrogenation reaction due to the strong Lewis acidity, which is not conducive to improving the yield of isobutylene. At the same time, the reproducibility of the catalytic results is poor, and it is difficult to obtain widespread application in industry.

[0004] Currently, non-precious metal catalysts have gradually become the research focus in this field due to their environmental friendliness and low cost. However, non-precious metal catalysts have low catalytic activity and are prone to decrease in catalytic activity due to metal coking during catalytic reactions. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a non-precious metal two-component composite molecular sieve catalyst with high activity, reproducibility, high dispersion and good reusability, as well as a preparation method and application thereof. A silicon-based molecular sieve material is used as a carrier, and a two-time impregnation or grinding method is adopted to introduce a non-precious metal two-component active center. The synthesis method is simple and easy to scale up to prepare the catalyst. The two components are loaded in a certain proportion to obtain a non-precious metal two-component composite molecular sieve catalyst. The molecular sieve surface is enriched with silicon hydroxyl grafted metal centers, and the high specific surface area and regular pore structure of the molecular sieve porous material are utilized to promote metal dispersion and stability. The first non-precious metal component automatically captures the second non-precious metal component and produces an electronic modulation effect between the two metal components. Combined with the reasonable regulation of the metal center loading ratio and the reasonable optimization of the reaction conditions, it can effectively and efficiently convert alkanes into olefins and produce hydrogen as a by-product.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A non-precious metal two-component composite molecular sieve catalyst comprises a carrier and an active component loaded on the carrier; the active component comprises a first non-precious metal and a second non-precious metal; the first non-precious metal and the second non-precious metal are independently selected from one or more of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium, and the first non-precious metal and the second non-precious metal are different; the carrier is a silicon-based molecular sieve.

[0008] The present invention also discloses a method for preparing the above-mentioned non-precious metal two-component composite molecular sieve catalyst, comprising the following steps:

[0009] (1) grinding and mixing a first non-noble metal precursor salt and a silicon-based molecular sieve or successively impregnating an aqueous solution containing the first non-noble metal precursor salt and the silicon-based molecular sieve to obtain a first component and a carrier mixture;

[0010] (2) drying and calcining the first component and the carrier mixture in sequence to obtain a molecular sieve loaded with a first non-precious metal;

[0011] (3) grinding and mixing the molecular sieve loaded with the first non-precious metal and the second non-precious metal precursor salt or mixing with their aqueous solution for successive impregnation to obtain a mixture of the two components and the carrier;

[0012] (4) The dual-component and carrier mixture is dried and calcined in sequence to obtain a non-precious metal dual-component composite molecular sieve catalyst.

[0013] The present invention also discloses an application of the non-precious metal two-component composite molecular sieve catalyst as described above, or the non-precious metal two-component composite molecular sieve catalyst prepared by the above-mentioned preparation method in the dehydrogenation of propane to propylene, the dehydrogenation of butane to butylene / butadiene, or the dehydrogenation of isobutane to isobutylene.

[0014] Implementing the embodiments of the present invention will have the following beneficial effects:

[0015] 1. The non-precious metal two-component composite molecular sieve catalyst provided in this application uses non-precious metal as the active center, and the acquisition and preparation process is low-cost and low-energy, which can reduce the production and preparation cost of the catalyst and improve economic benefits.

[0016] 2. The non-precious metal two-component composite molecular sieve catalyst provided in the present application exhibits high alkane dehydrogenation activity based on metal-metal interactions and electron modulation mechanisms, and obtains a higher olefin yield and high olefin selectivity under industrial conditions.

[0017] 3. The non-precious metal two-component composite molecular sieve catalyst provided in the present application has highly dispersed metal active centers. The characteristic micropores of the molecular sieve play a spatial confinement role to stabilize the metal centers and inhibit their coking and agglomeration during high-temperature reactions, thereby maintaining high reaction activity and catalyst stability.

[0018] 4. The non-precious metal two-component composite molecular sieve catalyst provided in this application has a simple regeneration process and can obtain the same catalytic dehydrogenation activity as a fresh catalyst through simple high-temperature air replacement and purge, and has good reusability.

[0019] 5. The non-precious metal two-component composite molecular sieve catalyst provided in this application has no toxic substances introduced during the preparation process, is environmentally friendly during use and recovery, does not cause secondary pollution, has a simple preparation method, and is easy to scale up and implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the XRD pattern of the dealuminated BEA carrier and the non-precious metal two-component composite molecular sieve catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA.

[0021] Figure 2 These are the hydroxyl infrared spectra of dealuminated BEA support and 0.7wt% Co-1.7wt% Zn / DeAlBEA.

[0022] Figure 3 This is the STEM image of the non-precious metal two-component composite molecular sieve catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA.

[0023] Figure 4 This is the XRD diagram of the non-precious metal two-component composite molecular sieve catalyst 2.4wt%Zn-5wt%Fe / Silicalite-1.

[0024] Figure 5 This is the STEM image of the non-precious metal two-component composite molecular sieve catalyst 2.4wt%Zn-5wt%Fe / Silicalite-1.

[0025] Figure 6 This is the performance diagram of propane dehydrogenation reaction catalyzed by the non-precious metal two-component composite molecular sieve catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA.

[0026] Figure 7 This is a graph showing the catalytic propane dehydrogenation reaction performance and regeneration performance of the non-precious metal two-component composite molecular sieve catalyst 1.4wt% Co-3.4wt% La / SPP.

[0027] Figure 8 This is the performance diagram of butane dehydrogenation reaction catalyzed by the non-precious metal two-component composite molecular sieve catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA.

[0028] Fig. 9 This is the performance diagram of propane dehydrogenation reaction catalyzed by non-precious metal single-component Zn molecular sieve catalyst 1.7wt% Zn / DeAlBEA. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0030] The invention discloses a non-precious metal two-component composite molecular sieve catalyst, comprising a carrier and an active component loaded on the carrier; the active component comprises a first non-precious metal and a second non-precious metal; the first non-precious metal and the second non-precious metal are independently selected from one or more of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium, and the first non-precious metal and the second non-precious metal are different; the carrier is a silicon-based molecular sieve.

[0031] In a specific embodiment, the loading amount of the first non-precious metal in the non-precious metal two-component composite molecular sieve catalyst is 0.3wt% to 15wt%. Preferably, the upper limit of the loading amount can be selected from 0.35wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 2.0wt%, 5.0wt%, 8.0wt%, 10wt%, 12wt% or 15wt%, and the lower limit can be selected from 0.3wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 2.0wt%, 5.0wt%, 8.0wt%, 10wt%, 12wt% or 14.5wt%.

[0032] In a specific embodiment, the loading amount of the second non-precious metal in the non-precious metal two-component composite molecular sieve catalyst is 0.3wt% to 15wt%. Preferably, the upper limit of the loading amount can be selected from 0.35wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 2.0wt%, 5.0wt%, 8.0wt%, 10wt%, 12wt% or 15wt%, and the lower limit can be selected from 0.3wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 2.0wt%, 5.0wt%, 8.0wt%, 10wt%, 12wt% or 14.5wt%.

[0033] In a specific embodiment, the silicon-based molecular sieve includes one or more of Si-BEA, dealuminated BEA, silicon-based SPP, Silicalite-1, SBA-15, pure silicon MEL, MCM-41, FAU and EMT molecular sieves.

[0034] In one specific embodiment, the method for preparing dealuminated BEA comprises the following steps:

[0035] (1) 13 mol / L nitric acid and 7 g HBEA zeolite were soaked in a mass ratio of 27:1 to obtain a mixed suspension.

[0036] (2) The mixed suspension was stirred at 100° C. at a speed of 20 r / min for 20 h, and the solid suspension obtained after heating and stirring was washed with deionized water in a sand core funnel until the pH of the supernatant was ≈ 7.

[0037] (3) The molecular sieve material after being fully washed in step (2) was dried at 120° C. for 4 h, and then ground into a uniform powder to obtain dealuminated BEA, which was recorded as DeAlBEA.

[0038] The present invention also discloses a method for preparing a non-precious metal two-component composite molecular sieve catalyst as in any embodiment, comprising the following steps:

[0039] (1) Grinding and mixing a first non-precious metal precursor salt and a silicon-based molecular sieve or successively impregnating and mixing an aqueous solution containing the first non-precious metal precursor salt and a silicon-based molecular sieve to obtain a first component and a carrier mixture.

[0040] (2) The first component and the carrier mixture are dried and calcined in sequence to obtain a molecular sieve loaded with the first non-precious metal.

[0041] In a specific embodiment, in step (2), the drying temperature is 20°C to 120°C; the drying time is 0.5h to 24h; the calcination temperature is 350°C to 700°C; and the calcination time is 2h to 10h.

[0042] (3) Grinding and mixing the molecular sieve loaded with the first non-precious metal and the second non-precious metal precursor salt or successively impregnating and mixing with an aqueous solution containing the second non-precious metal precursor salt to obtain a mixture of the two components and the carrier.

[0043] (4) The mixture of the two components and the carrier is dried and calcined in sequence to obtain a non-precious metal two-component composite molecular sieve catalyst.

[0044] In a specific embodiment, in step (4), the drying temperature is 20°C to 120°C; the drying time is 0.5h to 24h; the calcination temperature is 350°C to 700°C; and the calcination time is 2h to 10h.

[0045] In a specific embodiment, the first non-precious metal precursor salt is selected from one or more of the nitrates, sulfates or chlorides of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium; the second non-precious metal precursor salt is selected from one or more of the nitrates, sulfates or chlorides of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium.

[0046] The present invention also discloses an application of a non-precious metal two-component composite molecular sieve catalyst as in any embodiment, or a non-precious metal two-component composite molecular sieve catalyst prepared by a preparation method as in any embodiment, in the dehydrogenation of propane to produce propylene, the dehydrogenation of butane to produce butylene / butadiene, or the dehydrogenation of isobutane to produce isobutylene.

[0047] In a specific embodiment, the application includes the following steps: in a fixed bed reactor, introducing alkane feed gas to react with a non-precious metal two-component composite molecular sieve catalyst to generate olefins and produce hydrogen as a by-product.

[0048] In a specific embodiment, the reaction pressure of propane dehydrogenation to propylene is 0.2 bar to 3 bar, the reaction temperature is 500° C. to 750° C., and the volume fraction of propane in the propane feed gas is 2% to 100%. Preferably, the reaction temperature is 500° C. to 600° C., the reaction pressure is 0.5 bar to 2.5 bar, and the volume fraction of alkanes in the feed gas is 10% to 50%.

[0049] The following are specific embodiments

[0050] Example 1

[0051] Catalyst 1 with a mass fraction of 0.7wt% Co-1.7wt% Zn / DeAlBEA was prepared by impregnation method using dealuminated BEA molecular sieve as a carrier. A zinc nitrate solution (0.087mol / L, 2.876g) was prepared and impregnated on DeAlBEA (1g). After drying at room temperature for 10h, it was dried at 50℃ for 30min. After being fully ground, it was dried at 120℃ in air for 2h, and then calcined at 550℃ for 4h to obtain 1.7wt% Zn / DeAlBEA. A cobalt nitrate solution (0.0435mol / L, 2.835g) was prepared and impregnated on 1.7wt% Zn / DeAlBEA (1g). After being dried at room temperature for 10h, it was dried at 50℃ for 30min. After being fully ground, it was dried at 120℃ in a nitrogen atmosphere for 2h, and then calcined at 550℃ for 4h to obtain a non-precious metal two-component composite catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA.

[0052] Figure 1 Figure 2 shows the XRD diagram of the carrier DeAlBEA and the obtained catalyst material 0.7wt% Co-1.7wt% Zn / DeAlBEA. By comparison, it is found that the materials have typical BEA structural characteristic peaks before and after the two non-precious metals are introduced into dealuminated BEA, indicating that the carrier and the catalyst always maintain a complete BEA structure after loading the metal, and the introduction of the metal does not destroy the crystal structure of the material.

[0053] Figure 2The infrared spectrum of the hydroxyl vibration of the carrier DeAlBEA and the obtained catalyst material 0.7wt% Co-1.7wt% Zn / DeAlBEA. As can be seen from the figure, the carrier surface is rich in molecular sieve inner surface silanol groups and hydrogen-bonded nested silanol groups, which provide riveting sites for the introduction of metal centers. After the introduction of metal components, the infrared peak intensity of molecular sieve inner surface silanol groups and hydrogen-bonded nested silanol groups decreased significantly, indicating that the metal center is grafted into the molecular sieve pores and surface through the condensation reaction process with silanol groups.

[0054] Figure 3 This is the STEM image of 0.7wt% Co-1.7wt% Zn / DeAlBEA, which has obvious BEA molecular sieve lattice stripe characteristics. The white bright spots in the image represent the bimetallic component species. The bimetallic component species on the catalyst are evenly distributed and highly dispersed, with a particle size of only about 2nm, and the accessibility of the metal species is high.

[0055] Example 2

[0056] Using Silicalite-1 as a carrier, catalyst 2 with a mass fraction of 2.4wt% Zn-5wt% Fe / Silicalite-1 was prepared by an equal volume impregnation method. A ferric chloride solution (0.32mol / L, 2.95g) was prepared and impregnated on Silicalite-1 (1g). After drying at room temperature for 12h, it was dried at 50℃ for 2h. After being fully ground, it was dried at 120℃ in air for 2h, and then calcined at 550℃ for 6h to obtain 5wt% Fe / Silicalite-1; a zinc nitrate solution (0.13mol / L, 2.908g) was prepared and impregnated on 5wt% Fe / Silicalite-1 (1g). After being dried at room temperature for 10h, it was dried at 50℃ for 2h. After being fully ground, it was dried at 120℃ in air atmosphere for 2h, and then calcined at 550℃ for 6h to obtain a non-precious metal two-component composite catalyst 2.4wt% Zn-5wt% Fe / Silicalite-1. Figure 4 This is the XRD diagram of the obtained catalyst material 2.4wt% Zn-5wt% Fe / Silicalite-1. The catalyst has the typical MFI molecular sieve crystal characteristic diffraction peaks of Silicalite-1, indicating that it has an MFI structure and the metal loading does not change the crystal configuration of the carrier. Figure 5 This is the STEM image of 2.4wt% Zn-5wt% Fe / Silicalite-1, where the white bright spots represent the center of the ZnFe bimetallic component. The bimetallic component species are evenly distributed and highly dispersed, with a particle size of only about 2nm, and the accessibility of the metal species is high.

[0057] Example 3

[0058] Using silicon-based SPP molecular sieve as a carrier, catalyst 3 with a mass fraction of 1.4wt% Co-3.4wt% La / SPP was prepared by an equal volume impregnation method. A lanthanum nitrate solution (0.087mol / L, 2.905g) was prepared and impregnated on a silicon-based SPP (1g). After drying at room temperature for 15h, drying at 50°C for 20min, drying at 120°C in air for 2h, and then calcined at 500°C for 6h to obtain 3.4wt% La / SPP; a cobalt nitrate solution (0.087mol / L, 2.87g) was prepared and impregnated on 3.4wt% La / SPP (1g). After drying at room temperature for 8h, drying at 50°C for 20min, drying at 120°C in a nitrogen atmosphere for 2h, and calcined at 560°C for 5h, a non-precious metal two-component composite catalyst 1.4wt% Co-3.4wt% La / SPP was obtained.

[0059] Example 4

[0060] Using Si-BEA molecular sieve as a carrier, catalyst 4 with a mass fraction of 2.5wt% Fe-5wt% Ga / Si-BEA was prepared by an equal volume impregnation method. A gallium chloride solution (0.245mol / L, 2.927g) was prepared and impregnated on Si-BEA (1g). After drying at room temperature for 12h, it was dried at 50℃ for 30min. After being fully ground, it was dried at 120℃ in air for 2h, and then calcined at 600℃ for 4h to obtain 5wt% Ga / Si-BEA. A ferric chloride solution (0.158mol / L, 2.87g) was prepared and impregnated on 5wt% Ga / Si-BEA (1g). After being dried at room temperature for 8h, it was dried at 50℃ for 30min. After being fully ground, it was dried at 120℃ in air atmosphere for 2h, and then calcined at 550℃ for 4h to obtain a non-precious metal two-component composite catalyst 2.5wt% Fe-5wt% Ga / Si-BEA.

[0061] Example 5

[0062] Using dealuminated BEA molecular sieve as a carrier, a grinding method was used to prepare catalyst 5 with a mass fraction of 0.7wt% Co-1.7wt% Zn / DeAlBEA. 2.876g of zinc nitrate solid and DeAlBEA molecular sieve (1g) were fully ground and mixed, dried at 50°C for 30min, dried at 120°C in an air atmosphere for 2h, and then calcined at 550°C for 4h to obtain 1.7wt% Zn / DeAlBEA; 2.835g of cobalt nitrate solid and 1.7wt% Zn / DeAlBEA (1g) were fully ground and mixed, dried at 50°C for 30min, dried at 120°C in an air atmosphere for 2h, and then calcined at 550°C for 4h to obtain a non-precious metal two-component composite catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA.

[0063] Example 6

[0064] Catalyst 1 was loaded into a fixed bed reactor, and a propane-nitrogen mixed gas with a propane volume content of 10% was introduced. The reaction temperature was 600°C, the reaction pressure was 1 bar, and the reaction space velocity was 27.2 h -1 The reaction was continued for 5 minutes and then sampling and analysis were performed. The obtained propane conversion was 71%, the propylene selectivity was 99.0%, and the propylene yield was 70.3%. Figure 6 This is the reaction performance diagram of the non-precious metal two-component composite molecular sieve catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA. After 120 minutes of reaction, the catalyst can maintain a stable propylene yield and a propylene selectivity of more than 99%.

[0065] Similarly, catalyst 5 was tested according to the method of Example 6, and it was found that catalyst 5 could achieve the same effect as catalyst 1.

[0066] Example 7

[0067] Catalyst 2 was loaded into a fixed bed reactor, and a propane-nitrogen mixed gas with a propane volume content of 20% was introduced. The reaction temperature was 580°C, the reaction pressure was 1 bar, and the reaction space velocity was 27.2 h -1 The reaction was continued for 10 minutes and then sampling and analysis were performed. The obtained propane conversion rate was 63.2%, the propylene selectivity was 99.0%, and the propylene yield was 62.6%.

[0068] Example 8

[0069] Catalyst 4 was loaded into a fixed bed reactor, and a propane-nitrogen mixed gas with a propane volume content of 20% was introduced. The reaction temperature was 500°C, the reaction pressure was 1 bar, and the reaction space velocity was 20.0 h -1 The reaction was continued for 10 minutes and then sampling and analysis were performed. The obtained propane conversion rate was 34.8%, the propylene selectivity was 99.8%, and the propylene yield was 34.7%.

[0070] Example 9

[0071] Catalyst 3 was loaded into a fixed bed reactor, and a propane-nitrogen mixed gas with a propane volume content of 20% was introduced. The reaction temperature was 600°C, the reaction pressure was 1 bar, and the reaction space velocity was 20.0 h -1, and sampling and analysis were carried out after 10 minutes of reaction. At the initial stage of the reaction, the propane conversion rate was 68.0%, the propylene selectivity was 99.0%, and the propylene yield was 67.3%. After 120 minutes of reaction, the propane conversion rate was 62.2%, the propylene selectivity was 99.2%, and the propylene yield was 61.7%; then, the reaction gas was stopped, the reactor temperature was lowered to 550°C and 40ml / min of air was introduced for 60 minutes to regenerate the catalyst; after the regeneration, the reactor temperature was raised to 600°C again, and 40ml / min of nitrogen was introduced for 10 minutes, and then a propane-nitrogen mixed gas with a propane volume content of 20% was continued to be introduced, with the reaction temperature being 600°C, the reaction pressure being 1 bar, and the reaction space velocity being 20h -1 The reaction was carried out under the conditions of 10 minutes for sampling and analysis; the initial propane conversion rate after the catalyst was regenerated once was 68.0%, the propylene selectivity was 99.0%, and the propylene yield was 67.3%. After 120 minutes of reaction, the propane conversion rate was 62.0%, the propylene selectivity was 99.2%, and the propylene yield was 61.5%. The same method was used for repeated regeneration and evaluation. Figure 7 This is a reaction and regeneration performance diagram of the catalyst 1.4wt% Co-3.4wt% La / SPP. After the catalyst is regenerated three times, the propylene yield can still be consistent with that of the fresh catalyst, indicating that the catalyst of the present application can maintain a relatively stable catalytic activity.

[0072] Example 10

[0073] Catalyst 1 was loaded into a fixed bed reactor, and a butane-nitrogen mixed gas with a butane volume content of 2.5% was introduced. The reaction temperature was 550°C, the reaction pressure was 1 bar, and the reaction space velocity was 13.6 h -1 The reaction was continued for 5 minutes and then sampling and analysis were performed. The obtained butane conversion rate was 63.2%, butadiene selectivity was 35.4%, and C4 product selectivity was 98.1%. Figure 8 This is the reaction performance diagram of the non-precious metal two-component composite molecular sieve catalyst 0.7wt% Co-1.7wt% Zn / DeAlBEA. After 120 minutes of reaction, the catalyst can maintain a high butadiene selectivity and a C4 product selectivity of more than 98%.

[0074] Embodiment 11

[0075] Catalyst 1 was loaded into a fixed bed reactor, and an isobutane-nitrogen mixed gas with an isobutane volume content of 2.5% was introduced. The reaction temperature was 550°C, the reaction pressure was 1 bar, and the reaction space velocity was 13.6 h -1 The reaction was continued for 5 minutes and the sampling and analysis were performed. The isobutane conversion rate was 57% and the isobutene selectivity was 97%.

[0076] Comparative Example 1

[0077] Catalyst 6 with a mass fraction of 1.7 wt% Zn / DeAlBEA was prepared by impregnation method using dealuminated BEA molecular sieve as a carrier. A zinc nitrate solution (0.087 mol / L, 2.876 g) was prepared and impregnated on DeAlBEA (1 g). The catalyst was dried at room temperature for 10 h, then dried at 50°C for 30 min, fully ground and dried in air at 120°C for 2 h, and then calcined at 550°C for 4 h to obtain 1.7 wt% Zn / DeAlBEA.

[0078] Catalyst 6 was loaded into a fixed bed reactor, and a propane-nitrogen mixed gas with a propane volume content of 10% was introduced. The reaction temperature was 600°C, the reaction pressure was 1 bar, and the reaction space velocity was 27.2 h -1 The reaction was continued for 10 minutes and then sampling and analysis were performed. The obtained propane conversion rate was 30.5%, the propylene selectivity was 98.0%, and the propylene yield was 29.9%. Fig. 9 This is the reaction performance diagram of the non-precious metal single-component Zn molecular sieve catalyst 1.7wt% Zn / DeAlBEA. After 120 minutes of reaction, the propylene yield and propylene selectivity of the catalyst remain stable, but are significantly lower than those of the non-precious metal two-component molecular sieve catalyst.

[0079] It can be seen that the present invention first undergoes a condensation reaction and grafting with the first metal component and the silanol group on the surface of the molecular sieve carrier. The first metal component that is preferentially introduced can automatically capture the second metal component and form a non-precious metal two-component composite structure. The non-precious metal two-component active center thus constructed can realize the efficient dehydrogenation of propane to propylene process, and exhibits a high alkane conversion rate that is significantly better than that of the single-metal component molecular sieve catalyst in the alkane dehydrogenation to propylene reaction. In addition, after the catalyst is regenerated at 550°C, the catalyst can still restore the catalytic activity and maintain a stable propane conversion rate for a long time. At the same time, the catalyst of the present application can realize a low-cost catalyst preparation process, and obtain a higher propane conversion rate under the conditions of low operating temperature, low energy consumption, and low equipment requirements, and has excellent application prospects in industry.

[0080] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A non-precious metal two-component composite molecular sieve catalyst, It is characterized in that It includes a carrier and an active component loaded on the carrier; The active component includes a first non-precious metal and a second non-precious metal; The first non-precious metal and the second non-precious metal are independently selected from one or more of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium, and the first non-precious metal and the second non-precious metal are different; The carrier is a silicon-based molecular sieve.

2. The non-precious metal two-component composite molecular sieve catalyst according to claim 1, It is characterized in that The loading amount of the first non-precious metal in the non-precious metal two-component composite molecular sieve catalyst is 0.3wt% to 15wt%; The loading amount of the second non-precious metal in the non-precious metal dual-component composite molecular sieve catalyst is 0.3 wt % to 15 wt %.

3. The non-precious metal two-component composite molecular sieve catalyst according to claim 1, It is characterized in that The silicon-based molecular sieve includes one or more of Si-BEA, dealuminated BEA, silicon-based SPP, Silicalite-1, SBA-15, pure silicon MEL, MCM-41, FAU and EMT molecular sieves.

4. A method for preparing a non-precious metal dual-component composite molecular sieve catalyst as claimed in any one of claims 1 to 3, It is characterized in that The following steps are involved: (1) loading a first non-noble metal precursor salt onto a silicon-based molecular sieve by grinding or impregnation with an aqueous solution to obtain a first component and a carrier mixture; (2) drying and calcining the first component and the carrier mixture in sequence to obtain a molecular sieve loaded with a first non-precious metal; (3) mixing the molecular sieve loaded with the first non-noble metal and the precursor salt of the second non-noble metal by grinding or impregnation with an aqueous solution to obtain a mixture of a non-noble metal dual component and a carrier; (4) The non-precious metal two-component and carrier mixture is dried and calcined in sequence to obtain a non-precious metal two-component composite molecular sieve catalyst.

5. The non-precious metal two-component composite molecular sieve catalyst according to claim 4, It is characterized in that The first non-noble metal precursor salt is selected from one or more of nitrates, sulfates or chlorides of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium; The second non-noble metal precursor salt is selected from one or more of nitrates, sulfates or chlorides of cobalt, zinc, iron, lanthanum, yttrium, indium and gallium.

6. The non-precious metal two-component composite molecular sieve catalyst according to claim 4, It is characterized in that In step (2), the drying temperature is 20°C to 120°C; the drying time is 0.5h to 24h; the calcining temperature is 350°C to 700°C; and the calcining time is 2h to 10h.

7. The non-precious metal two-component composite molecular sieve catalyst according to claim 4, It is characterized in that In step (4), the drying temperature is 20°C to 120°C; the drying time is 0.5h to 24h; the calcination temperature is 350°C to 700°C; and the calcination time is 2h to 10h.

8. An application of the non-precious metal two-component composite molecular sieve catalyst as described in any one of claims 1 to 3, or the non-precious metal two-component composite molecular sieve catalyst prepared by the preparation method as described in any one of claims 4 to 7 in the dehydrogenation of propane to propylene, the dehydrogenation of butane to butylene / butadiene, or the dehydrogenation of isobutane to isobutylene.

9. The use according to claim 8, It is characterized in that The application comprises the following steps: in a fixed bed reactor, introducing a raw gas to react with the non-precious metal two-component composite molecular sieve catalyst to generate olefins and by-product hydrogen.

10. The use according to claim 9, It is characterized in that The reaction pressure of the dehydrogenation is 0.2 bar to 3 bar, the reaction temperature is 500° C. to 750° C., and the volume fraction of alkanes in the raw gas is 2% to 100%.

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