High-efficiency stable hydrophobic bifunctional catalyst and preparation method and application thereof

Abstract

This invention discloses a highly efficient and stable hydrophobic bifunctional catalyst, its preparation method, and its application, belonging to the fields of biochemical engineering and catalysis technology. The catalyst uses a La-doped MFI hierarchical porous molecular sieve as a support, loading an active component and a hydrophobic modifier. The active component consists of a Co-YPO4 complex (main active component) and one or two of Ag and Cu (co-active components). The hydrophobic modifier is polyvinylbenzene or the silane coupling agent KH-570. The preparation method includes three steps: preparation of the La-doped MFI hierarchical porous molecular sieve, loading of the active component, and hydrophobic modification. This catalyst, through La doping to regulate the acid-base active site balance, the synergistic effect of Co-YPO4 and the co-active component to improve catalytic efficiency, and the enhancement of water resistance and anti-carbon deposition ability by the hydrophobic modifier, can directly catalyze the conversion of aqueous ethanol with an ethanol conversion rate ≥85% and butadiene selectivity ≥78%. It overcomes the core defects of existing catalysts and is suitable for continuous industrial production.

Description

Technical Field

[0001] This invention belongs to the technical field of biochemical engineering and catalysis, and specifically discloses a highly efficient and stable hydrophobic bifunctional catalyst, its preparation method and application. Background Technology

[0002] 1,3-Butadiene is a core monomer for bulk chemicals such as synthetic rubber and engineering plastics, with huge global market demand. Currently, its production mainly relies on the petroleum route. With the depletion of fossil resources and the advancement of the "dual carbon" strategy, the preparation of butadiene from renewable bioethanol has become a research hotspot in the industry. The core of the bioethanol-to-butadiene preparation process is the catalytic reaction. The performance of the catalyst directly determines the reaction efficiency, product selectivity, and industrial feasibility. Among them, the one-step process has become the mainstream research direction due to its simple process and good economy. However, the catalysts used in the existing one-step process have many core defects, which seriously restrict the implementation of the technology.

[0003] (1) Imbalance of acid-base active sites: Existing catalysts are mainly MgO / SiO2 system, metal oxide system or ordinary molecular sieve-based catalysts. The ratio of Lewis acid sites to Bronsted acid sites is unreasonable, which leads to poor synergy between the dehydrogenation of ethanol to acetaldehyde and the condensation of acetaldehyde to butadiene. Either the butadiene selectivity is low (usually less than 65%) and there are more by-products (ethylene, diethyl ether, brown oil, etc.); or the ethanol conversion rate is insufficient and cannot meet the needs of industrial production capacity.

[0004] (2) Poor water resistance: The fermentation products of bioethanol are mostly ethanol-water azeotropes (ethanol mass fraction 60-80%). Separating and purifying anhydrous ethanol is energy-intensive. Most existing catalysts have many hydrophilic sites on their surface, and water molecules can easily poison the catalytic active sites, resulting in a significant decrease in catalyst activity or even rapid deactivation when using aqueous ethanol directly.

[0005] (3) Insufficient stability: Existing catalysts are prone to carbon buildup and loss of active components. They have short operating cycles (usually less than 100 hours) and require frequent regeneration, which not only increases production energy consumption and costs but also affects the continuity of the reaction, making it difficult to meet the needs of continuous industrial production.

[0006] In the existing technology, the relevant improvement solutions still have obvious limitations: the MFI molecular sieve-supported ZnO and Zr catalyst disclosed in patent CN117500592A has an ethanol conversion rate of 97.9%, but the butadiene selectivity is only 38.7%, which is extremely poor catalytic selectivity; the Zr-based MFI molecular sieve catalyst disclosed in patent CN113996330B has a butadiene selectivity of 70%, but the ethanol conversion rate is only 40%, which cannot balance activity and selectivity; the Co-YPO4 bifunctional catalyst developed by Dalian University of Technology has improved the catalytic activity to a certain extent, but it still has problems such as insufficient stability and poor water resistance, and the operating cycle is less than 80 hours. Moreover, it has not solved the core problem of acid-base site synergy.

[0007] Therefore, developing a dedicated catalyst that combines precisely regulated acid-base active sites, good water resistance, high stability, and high catalytic efficiency, and overcoming the core defects of existing catalysts, is key to the industrialization of bioethanol to butadiene production technology. Summary of the Invention

[0008] To address the technical shortcomings of existing bioethanol-to-butadiene catalysts, such as acid-base imbalance, poor water resistance, insufficient stability, low catalytic efficiency, and numerous byproducts, this invention provides a highly efficient, stable, hydrophobic bifunctional catalyst and its preparation method. This catalyst is then applied to the bioethanol-to-butadiene production process. Through support modification, synergistic design of active components, and hydrophobic modification, the catalyst achieves simultaneous improvements in catalytic activity, selectivity, stability, and water resistance. It is suitable for the direct catalytic conversion of aqueous ethanol feedstocks, thereby reducing industrial catalytic costs.

[0009] To achieve the above objectives, the present invention first provides a highly efficient and stable hydrophobic bifunctional catalyst, wherein the catalyst is a rare earth metal modified hydrophobic bifunctional molecular sieve catalyst, with a La-doped MFI hierarchical porous molecular sieve as the support, and loaded with active components and hydrophobic modifiers. The components are as follows by mass percentage: active component 5-15%, hydrophobic modifier 2-8%, and La-doped MFI hierarchical porous molecular sieve 77-93%.

[0010] Preferably, the components in the high-efficiency, stable, hydrophobic bifunctional catalyst are as follows by mass percentage: 8-12% active component, 4-6% hydrophobic modifier, and 82-90% La-doped MFI hierarchical porous molecular sieve.

[0011] The active component consists of a main active component and a co-active component. The main active component is a Co-YPO4 complex, and the co-active component is one or two of Ag and Cu mixed in any proportion. The mass ratio of the main active component to the co-active component is 3-5:1.

[0012] Preferably, the mass ratio of the main active component to the auxiliary active component is 4:1, and the mass ratio of the auxiliary active component Ag to Cu is 1:1.

[0013] The hydrophobic modifier is polyvinylbenzene or silane coupling agent KH-570.

[0014] Preferably, the hydrophobic modifier is polyvinylbenzene, used to reduce hydrophilic sites on the catalyst surface and inhibit the poisoning of active sites by water molecules and the formation of carbon deposits.

[0015] Furthermore, the La-doped MFI hierarchical porous molecular sieve exhibits a microporous-mesoporous coexistence structure with a specific surface area of ​​350-550 m². 2 / g, with mesopore sizes of 2-50 nm and micropore sizes of 0.5-1.0 nm; the doping amount of La is 1-3% of the molecular sieve mass. The core function of La-doped MFI hierarchical porous molecular sieves is to precisely control the distribution of acid-base active sites in the molecular sieve, balance the ratio of Lewis acid sites and weakly Bronsted acid sites, promote the synergistic process of ethanol dehydrogenation and acetaldehyde condensation reaction, and at the same time enhance the structural stability of the support and inhibit the loss of active components.

[0016] The Co-YPO4 complex is prepared as follows: Cobalt nitrate, yttrium nitrate, and ammonium dihydrogen phosphate are dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.2-1.5:1.0-1.2. After stirring evenly, the pH is adjusted to 4.5-5.5, and the mixture is stirred at a constant temperature of 60-80℃ for 2-4 hours. The mixture is then transferred to a hydrothermal reactor and hydrothermally reacted at 120-150℃ for 8-12 hours. After cooling, filtration, washing, and drying, the mixture is calcined at 450-550℃ for 3-5 hours to obtain the Co-YPO4 complex. The Co-YPO4 complex exhibits good dispersibility and high activity.

[0017] Preferably, the molar ratio of Co:Y:P is 1:1.3:1.1, the hydrothermal reaction temperature is 130℃, the hydrothermal reaction time is 10h, the calcination temperature is 500℃, and the calcination time is 4h.

[0018] This invention also provides a method for preparing the above-mentioned highly efficient and stable hydrophobic bifunctional catalyst, specifically including the following steps:

[0019] S1, Preparation of La-doped MFI hierarchical porous molecular sieve: Silicon source, aluminum source, La source, template agent and deionized water are mixed and stirred to form a gel. The gel is transferred to a hydrothermal reactor for hydrothermal crystallization, filtered, washed with deionized water until neutral, dried and calcined to completely remove the template agent, and La-doped MFI hierarchical porous molecular sieve is obtained.

[0020] S2, Loading active components: The La-doped MFI hierarchical porous molecular sieve prepared in step S1 is dispersed in deionized water and ultrasonically dispersed. The main active component Co-YPO4 complex and the auxiliary active component are added and stirred at a constant temperature to allow the active components to be fully adsorbed and loaded on the surface and pores of the support. Then, it is evaporated and concentrated to dryness and dried to obtain the molecular sieve precursor.

[0021] S3. Hydrophobic modification: The molecular sieve precursor obtained in step S2 is dispersed in anhydrous ethanol, a hydrophobic modifier is added, and ultrasonic dispersion is performed to uniformly coat the surface of the molecular sieve precursor with the hydrophobic modifier. The mixture is then refluxed to allow the hydrophobic modifier to form stable chemical bonds with the molecular sieve precursor. After cooling to room temperature, the mixture is filtered, washed 2-3 times with anhydrous ethanol to remove unreacted hydrophobic modifier, and then dried to obtain the highly efficient, stable, hydrophobic bifunctional catalyst.

[0022] In step S1, the silicon source is tetraethyl orthosilicate, the aluminum source is aluminum isopropoxide, the La source is lanthanum nitrate, and the template agent is tetrapropylammonium hydroxide; the molar ratio of the silicon source, aluminum source, La source, template agent, and deionized water is Si:Al:La:template agent:H2O = 100:2-5:1-3:10-15:300-400; the hydrothermal crystallization temperature is 160-180℃, and the time is 24-36h; the drying temperature is 100-120℃, and the time is 12-24h; the calcination temperature is 550-650℃, and the time is 4-6h.

[0023] Preferably, the hydrothermal crystallization temperature in step S1 is 170°C and the time is 30 hours; the calcination temperature is 600°C and the time is 5 hours.

[0024] In step S2, the deionized water is 10-15 times the mass of the La-doped MFI hierarchical porous molecular sieve; the ultrasonic dispersion time is 30-60 min with a power of 80 W; the constant temperature stirring temperature is 60-80℃ for 4-6 h; and the drying temperature is 100-120℃ for 12-24 h.

[0025] Preferably, the ultrasonic dispersion time in step S2 is 45 min; the constant temperature stirring temperature is 70℃ for 5 h; and the drying temperature is 110℃ for 18 h.

[0026] In step S3, the ratio of the molecular sieve precursor mass to the volume of anhydrous ethanol is 1g:20-30mL; the ultrasonic dispersion time is 20-30min, and the power is 80W; the reflux reaction temperature is 80-100℃, and the time is 2-3h; the drying temperature is 110-130℃, and the time is 8-12h.

[0027] Preferably, the ultrasonic dispersion time in step S3 is 25 min; the reflux reaction temperature is 90 °C and the time is 2.5 h; and the drying temperature is 120 °C and the time is 10 h.

[0028] The present invention also provides the application of the above-described highly efficient and stable hydrophobic bifunctional catalyst in the one-step preparation of butadiene from bioethanol.

[0029] The aforementioned highly efficient, stable, hydrophobic bifunctional catalyst can directly catalyze the conversion of 60-80% (w / w) aqueous ethanol, at a reaction temperature of 280-320℃, a reaction pressure of 0.3-0.6 MPa, and a feed mass hourly space velocity of 0.8-1.5 h⁻¹. -1 The volume ratio of raw gas to nitrogen is 1:3.

[0030] Preferably, the reaction temperature is 300℃, the reaction pressure is 0.4 MPa, and the feed mass hourly space velocity is 1.2 h⁻¹. -1 Its beneficial effects are that, under these conditions, when the highly efficient and stable hydrophobic bifunctional catalyst prepared in this invention is used for the catalytic reaction of bioethanol (70% ethanol by mass, containing water) to prepare butadiene, the ethanol conversion rate is ≥85%, the butadiene selectivity is ≥78%, the butadiene yield is ≥66%, the operating cycle is 180-220 h / cycle, it can be regenerated 5-6 times, and the cumulative operating cycle is ≥1000 h. When using 70% aqueous ethanol directly, the catalytic activity does not decrease significantly (activity retention rate ≥95%). Existing MgO / SiO2 catalysts have an ethanol conversion rate of 65-70%, butadiene selectivity of 55-60%, butadiene yield of 35-42%, and an operating cycle of ≤80h. When using 70% aqueous ethanol directly, the catalytic activity decreases by more than 40%. Existing Co-YPO4 bifunctional catalysts have an ethanol conversion rate of 78-80%, butadiene selectivity of 68-70%, butadiene yield of 53-56%, and an operating cycle of ≤80h. When using 70% aqueous ethanol directly, the catalytic activity decreases by more than 30%.

[0031] In summary, this invention provides a highly efficient and stable hydrophobic bifunctional catalyst, its preparation method, and its application. Compared with existing technologies, the catalyst of this invention has the following significant advantages: (1) This invention is the first to organically integrate the La-doped MFI hierarchical porous molecular sieve support, Co-YPO4 main active component, Ag / Cu auxiliary active component and hydrophobic modifier to construct a bifunctional catalytic system of "support-main active-auxiliary active-hydrophobic modification", which is different from the existing single-function or simple mixed catalyst design. In existing technologies, MgO / SiO2 catalysts rely solely on single acid-base sites for catalysis, lacking synergistic activity of active components and hydrophobic protection, leading to frequent side reactions. Conventional Co-YPO4 bifunctional catalysts, while possessing basic dehydrogenation-coupling activity, fail to regulate acid-base site balance through rare earth doping or undergo hydrophobic modification, thus failing to address the issues of active site poisoning and loss. In contrast, this invention precisely regulates the ratio of Lewis acid sites to weakly Bronsted acid sites in the molecular sieve through La doping, forming a synergistic catalytic network with the (Co-OP) active species and Ag / Cu co-active components of the Co-YPO4 complex. Simultaneously, a hydrophobic surface layer is constructed using a hydrophobic modifier, achieving highly efficient synergy across the entire reaction process of "dehydrogenation-coupling-dehydration-anti-poisoning" at the mechanistic level. This avoids the limitations of single-active-component catalysis and solves the core problems of site imbalance and susceptibility to water molecule interference in existing synergistic systems.

[0032] (2) Based on the catalytic mechanism, it can be seen that the performance advantage of the catalyst of this invention is not a simple superposition of components, but a precise improvement achieved through the synergistic mechanism of each component. On the one hand, in the main active component Co-YPO4 complex, Co 2+ With PO4 3- The resulting stable (Co-OP) active species can efficiently catalyze the dehydrogenation of ethanol to acetaldehyde, while Y 3+The sites can adsorb and activate acetaldehyde molecules, promoting the C-C coupling reaction between two acetaldehyde molecules and breaking through the rate-controlling step of ethanol to butadiene conversion. The Ag / Cu co-active components can reduce the activation energy of the ethanol dehydrogenation reaction, further increasing the dehydrogenation rate, while inhibiting the loss of Co and Y active components, forming a "dehydrogenation-activation" synergistic effect with the main active components. On the other hand, the hierarchical porous structure of the La-doped MFI configuration hierarchical porous molecular sieve support can shorten the diffusion path of substances such as ethanol and butadiene, improve mass transfer efficiency, reduce the residence time of products in the pores, and reduce the probability of carbon deposition. The core role of La doping is to precisely control the distribution of acid-base active sites, so that the ratio of Lewis acid sites to weakly Bronsted acid sites is optimal, ensuring the efficient progress of the acetaldehyde condensation reaction and avoiding side reactions caused by strong Bronsted acid sites (such as intramolecular dehydration of ethanol to form diethyl ether, intermolecular dehydration to form ethylene, etc.). Based on this precise regulation at the mechanistic level, the catalyst of this invention achieves an ethanol conversion rate of ≥85%, a butadiene selectivity of ≥78%, and a butadiene yield of ≥66%, which is far superior to existing MgO / SiO2 catalysts (conversion rate 65-70%, selectivity 55-60%) and conventional Co-YPO4 bifunctional catalysts (conversion rate 78-80%, selectivity 68-70%). At the same time, it effectively inhibits the formation of by-products, reduces the difficulty of subsequent product separation, and improves the economics of industrial production.

[0033] (3) Bioethanol fermentation products are mostly azeotropic mixtures containing 60-80% aqueous ethanol. Separating and purifying anhydrous ethanol requires a large amount of energy. One of the core problems of existing catalysts is their poor water resistance. The root cause is that there are a large number of hydrophilic sites on the catalyst surface, and water molecules are easily adsorbed on the surface of the active sites, leading to poisoning of the active sites and a significant decrease in catalytic activity. This invention addresses this mechanistic problem by specifically introducing polyvinylbenzene or silane coupling agent KH-570 as a hydrophobic modifier. Through a reflux reaction, the hydrophobic modifier forms a stable chemical bond with the molecular sieve precursor, constructing a dense hydrophobic layer on the catalyst surface. From the perspective of the catalytic mechanism, this hydrophobic layer can effectively repel water molecules and prevent water molecules from entering the catalyst channels and interacting with the active sites (Co). 2+ Y 3+ The catalyst combines with La-regulated acid-base sites to prevent poisoning of active sites. Simultaneously, the hydrophobic layer inhibits the adsorption of polar byproducts (such as brown oil) on the catalyst surface during the reaction, further reducing carbon deposition. This fundamentally solves the technical bottleneck of existing catalysts being unable to directly adapt to aqueous ethanol feedstocks. Test results show that when the catalyst of this invention is used directly with 70% aqueous ethanol, the catalytic activity retention rate is ≥95%, while the activity of existing MgO / SiO2 catalysts decreases by more than 40%, and the activity of conventional Co-YPO4 bifunctional catalysts decreases by more than 30%. This significantly reduces the cost of industrial raw material pretreatment and improves the practicality of the technology.

[0034] (4) This invention addresses both the catalytic mechanism and structural design to achieve a comprehensive improvement in stability: First, the La-doped MFI hierarchical porous molecular sieve support exhibits excellent structural stability. The introduction of La enhances the rigidity of the molecular sieve framework and inhibits pore collapse. Simultaneously, the weak interaction between La and the active components (Co, Y, Ag, Cu) effectively suppresses the loss of active components. Second, the Ag / Cu co-active components not only enhance catalytic activity but also act as "stabilizers," forming a synergistic effect with the Co-YPO4 complex to reduce Co content. 2+ Y 3+ The catalyst exhibits several key advantages: firstly, it prevents oxidation and loss; secondly, the hydrophobic layer formed by the hydrophobic modifier inhibits the adsorption of water molecules and polar byproducts, reducing carbon buildup and preventing carbon deposits from covering active sites and causing catalyst deactivation; and thirdly, the hierarchical porous structure shortens the mass transfer path, reducing product retention within the pores and further decreasing the probability of carbon buildup. Based on these multiple mechanistic protections, the catalyst of this invention can achieve a single operating cycle of 180-220 hours, can be regenerated 5-6 times, and has a cumulative operating cycle ≥1000 hours, far superior to existing catalysts (single operating cycle ≤80 hours). This significantly reduces the frequency of catalyst replacement and regeneration, lowers production energy consumption and catalytic costs, and fully meets the needs of continuous industrial production. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 This is the chromatogram of the raw material ethanol.

[0037] Figure 2 The chromatogram is for the target product, butadiene.

[0038] Figure 3 This is the chromatogram of the gaseous products of the reaction.

[0039] Figure 4 This is the chromatogram of the liquid phase products from the reaction. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that, unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available conventional products; the test methods used are all conventional test methods; and the catalyst performance tests all adopted the same reaction conditions: a fixed-bed reactor, a reaction temperature of 300℃, a reaction pressure of 0.4MPa, and a raw material weight hourly space velocity of 1.2h. -1 The raw material is 70% aqueous ethanol, and the volume ratio of raw material gas to nitrogen is 1:3.

[0042] Example 1 The efficient and stable hydrophobic bifunctional catalyst prepared in this embodiment has the following mass percentages: 10% active component, 5% polyvinylbenzene (hydrophobic modifier), and 85% La-doped MFI hierarchical porous molecular sieve; wherein, the mass ratio of Co-YPO4 complex to Ag-Cu co-active component (Ag:Cu=1:1) in the active component is 4:1; and the La element doping amount is 2% of the molecular sieve mass.

[0043] The specific preparation steps are as follows: S1, Preparation of La-doped MFI hierarchical porous molecular sieve: Tetraethyl orthosilicate, aluminum isopropoxide, lanthanum nitrate, tetrapropylammonium hydroxide and deionized water were mixed in a molar ratio of Si:Al:La:template:H2O=100:3:2:12:350 and stirred until homogeneous to form a gel; the gel was transferred to a hydrothermal reactor and hydrothermally crystallized at 170℃ for 30h, filtered and washed until neutral, dried at 110℃ for 12h, calcined at 600℃ for 5h to remove the template agent, and the La-doped MFI hierarchical porous molecular sieve was obtained.

[0044] Nitrogen adsorption analysis revealed that its nitrogen adsorption-desorption curve exhibited a typical type IV isotherm with an H4 hysteresis loop, indicating that the molecular sieve has a multi-level pore structure with both micropores and mesopores. Calculations showed that its specific surface area was 426 m² / g, with mesopore sizes mainly distributed in the range of 8-25 nm (average mesopore size 16.8 nm) and micropore sizes mainly distributed in the range of 0.55-0.85 nm (average micropore size 0.72 nm).

[0045] S2, Preparation of Co-YPO4 complex: Cobalt nitrate, yttrium nitrate and ammonium dihydrogen phosphate were dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.3:1.1. After stirring evenly, the pH was adjusted to 5.0, and the mixture was stirred at 70℃ for 3 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 130℃ for 10 hours. After cooling, the mixture was filtered, washed, dried at 110℃ for 12 hours, and calcined at 500℃ for 4 hours to obtain the Co-YPO4 complex.

[0046] S3, Loading active components: The carrier prepared in step S1 is dispersed in 10 times its mass of deionized water, ultrasonically dispersed for 45 min at a power of 80 W, and a preset amount of Co-YPO4 complex and Ag-Cu auxiliary active components are added. The mixture is stirred at 70℃ for 5 h, evaporated and concentrated to dryness, and dried at 110℃ for 18 h to obtain the molecular sieve precursor.

[0047] S4. Hydrophobic modification: The molecular sieve precursor was dispersed in anhydrous ethanol at a ratio of 1 g of molecular sieve precursor to 25 mL of anhydrous ethanol. Polyvinylbenzene was added, and the mixture was ultrasonically dispersed for 25 min at a power of 80 W. The mixture was then refluxed at 90 °C for 2.5 h. After cooling, the mixture was filtered, washed, and dried at 120 °C for 10 h to obtain a highly efficient and stable hydrophobic bifunctional catalyst.

[0048] Performance testing: The catalyst achieved an ethanol conversion rate of 88.2%, a butadiene selectivity of 79.5%, and a butadiene yield of 69.1%. After 200 hours of continuous operation, the catalytic activity retention rate was 96.3%. After five regeneration cycles, the catalytic activity did not decrease significantly.

[0049] Example 2 The efficient and stable hydrophobic bifunctional catalyst prepared in this embodiment has the following mass percentages: active component 8%, silane coupling agent KH-570 (hydrophobic modifier) ​​4%, and La-doped MFI hierarchical porous molecular sieve 88%; wherein, the mass ratio of Co-YPO4 complex to Ag co-active component in the active component is 3:1; and the La element doping amount is 1% of the molecular sieve mass.

[0050] The specific preparation steps are as follows: S1. Preparation of La-doped MFI hierarchical porous molecular sieve: Tetraethyl orthosilicate, aluminum isopropoxide, lanthanum nitrate, tetrapropylammonium hydroxide and deionized water were mixed in a molar ratio of Si:Al:La:template:H2O=100:2:1:10:300 and stirred until homogeneous to form a gel; the gel was transferred to a hydrothermal reactor and hydrothermally crystallized at 160℃ for 24h, filtered and washed until neutral, dried at 100℃ for 24h, calcined at 550℃ for 6h to remove the template agent, and La-doped MFI hierarchical porous molecular sieve was obtained.

[0051] Nitrogen adsorption analysis revealed that its nitrogen adsorption-desorption curve exhibited a typical type IV isotherm with an H4 type hysteresis loop, indicating that the molecular sieve has a multi-level pore structure with both micropores and mesopores. Calculations showed that its specific surface area was 389 m² / g, with mesopore sizes mainly distributed in the range of 6–20 nm (average mesopore size 13.5 nm) and micropore sizes mainly distributed in the range of 0.52–0.80 nm (average micropore size 0.68 nm).

[0052] S2. Preparation of Co-YPO4 complex: Cobalt nitrate, yttrium nitrate and ammonium dihydrogen phosphate were dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.2:1.0. After stirring evenly, the pH was adjusted to 4.5, and the mixture was stirred at 60℃ for 4 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 120℃ for 12 hours. After cooling, the mixture was filtered, washed, dried at 100℃ for 24 hours, and calcined at 450℃ for 5 hours to obtain the Co-YPO4 complex.

[0053] S3. Loading active components: Disperse the carrier prepared in step S1 in 10 times its mass of deionized water, sonicate for 30 min at 80 W, add the preset amount of Co-YPO4 complex and Ag co-active components, stir at 60℃ for 6 h, evaporate and concentrate to dryness, and dry at 100℃ for 24 h to obtain the molecular sieve precursor.

[0054] S4. Hydrophobic modification: The molecular sieve precursor was dispersed in anhydrous ethanol at a ratio of 1 g of molecular sieve precursor to 25 mL of anhydrous ethanol. Silane coupling agent KH-570 was added, and the mixture was ultrasonically dispersed for 20 min at 80 W. The mixture was then refluxed at 80 °C for 3 h. After cooling, the mixture was filtered, washed, and dried at 110 °C for 12 h to obtain a highly efficient and stable hydrophobic bifunctional catalyst.

[0055] Performance testing: The catalyst achieved an ethanol conversion rate of 85.1%, a butadiene selectivity of 78.3%, and a butadiene yield of 66.6%. After 180 hours of continuous operation, the catalytic activity retention rate was 95.7%. After six regeneration cycles, the catalytic activity did not decrease significantly.

[0056] Example 3 The efficient and stable hydrophobic bifunctional catalyst prepared in this embodiment has the following mass percentages: 12% active component, 6% polyvinylbenzene (hydrophobic modifier), and 82% La-doped MFI hierarchical porous molecular sieve; wherein, the mass ratio of Co-YPO4 complex to Cu co-active component in the active component is 5:1; and the La element doping amount is 3% of the molecular sieve mass.

[0057] The specific preparation steps are as follows: S1. Preparation of La-doped MFI hierarchical porous molecular sieve: Tetraethyl orthosilicate, aluminum isopropoxide, lanthanum nitrate, tetrapropylammonium hydroxide and deionized water were mixed in a molar ratio of Si:Al:La:template:H2O=100:5:3:15:400 and stirred until homogeneous to form a gel; the gel was transferred to a hydrothermal reactor and hydrothermally crystallized at 180℃ for 36h, filtered and washed until neutral, dried at 120℃ for 12h, calcined at 650℃ for 4h to remove the template agent, and the La-doped MFI hierarchical porous molecular sieve was obtained.

[0058] Nitrogen adsorption analysis revealed that its nitrogen adsorption-desorption curve exhibited a typical type IV isotherm with an H4 hysteresis loop, indicating that the molecular sieve has a multi-level pore structure with both micropores and mesopores. Calculations showed that its specific surface area was 457 m² / g, with mesopore sizes mainly distributed in the range of 10–30 nm (average mesopore size 19.2 nm) and micropore sizes mainly distributed in the range of 0.58–0.90 nm (average micropore size 0.76 nm).

[0059] S2. Preparation of Co-YPO4 complex: Cobalt nitrate, yttrium nitrate and ammonium dihydrogen phosphate were dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.5:1.2. After stirring evenly, the pH was adjusted to 5.5, and the mixture was stirred at 80℃ for 2 hours. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 150℃ for 8 hours. After cooling, the mixture was filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 3 hours to obtain the Co-YPO4 complex.

[0060] S3. Loading active components: Disperse the carrier prepared in step S1 in 10 times its mass of deionized water, sonicate for 60 min at 80 W, add the preset amount of Co-YPO4 complex and Cu auxiliary active components, stir at 80℃ for 4 h, evaporate and concentrate to dryness, and dry at 120℃ for 12 h to obtain the molecular sieve precursor.

[0061] S4. Hydrophobic modification: The molecular sieve precursor was dispersed in anhydrous ethanol at a ratio of 1 g of molecular sieve precursor to 25 mL of anhydrous ethanol. Polyvinylbenzene was added, and the mixture was ultrasonically dispersed for 30 min at a power of 80 W. The mixture was then refluxed at 100 °C for 2 h. After cooling, the mixture was filtered, washed, and dried at 130 °C for 8 h to obtain a highly efficient and stable hydrophobic bifunctional catalyst.

[0062] Performance testing: The catalyst achieved an ethanol conversion rate of 89.5%, a butadiene selectivity of 80.2%, and a butadiene yield of 71.8%. After continuous operation for 220 hours, the catalytic activity retention rate was 97.1%. After five regeneration cycles, the catalytic activity did not decrease significantly.

[0063] Example 4 The efficient and stable hydrophobic bifunctional catalyst prepared in this embodiment has the following mass percentages: 5% active component, 2% polyvinylbenzene (hydrophobic modifier), and 93% La-doped MFI hierarchical porous molecular sieve; wherein, the mass ratio of Co-YPO4 complex to Ag-Cu co-active component (Ag:Cu=2:1) ​​in the active component is 3:1; and the La element doping amount is 1% of the molecular sieve mass.

[0064] The specific preparation steps are as follows: S1. Preparation of La-doped MFI hierarchical porous molecular sieve: Tetraethyl orthosilicate, aluminum isopropoxide, lanthanum nitrate, tetrapropylammonium hydroxide and deionized water were mixed in a molar ratio of Si:Al:La:template:H2O=100:2:1:12:320 and stirred until homogeneous to form a gel; the gel was transferred to a hydrothermal reactor and hydrothermally crystallized at 165℃ for 28h, filtered and washed until neutral, dried at 105℃ for 20h, calcined at 580℃ for 5h to remove the template agent, and the La-doped MFI hierarchical porous molecular sieve was obtained.

[0065] Nitrogen adsorption analysis revealed that its nitrogen adsorption-desorption curve exhibited a typical type IV isotherm with an H4 hysteresis loop, indicating that the molecular sieve has a multi-level pore structure with both micropores and mesopores. Calculations showed that its specific surface area was 372 m² / g, with mesopore sizes mainly distributed in the range of 5–18 nm (average mesopore size 11.6 nm) and micropore sizes mainly distributed in the range of 0.50–0.78 nm (average micropore size 0.65 nm).

[0066] S2. Preparation of Co-YPO4 complex: Cobalt nitrate, yttrium nitrate and ammonium dihydrogen phosphate were dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.2:1.1. After stirring evenly, the pH was adjusted to 4.8, and the mixture was stirred at 65℃ for 3.5 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 125℃ for 11 h. After cooling, the mixture was filtered, washed, dried at 105℃ for 20 h, and calcined at 480℃ for 4.5 h to obtain the Co-YPO4 complex.

[0067] S3. Loading active components: The carrier prepared in step S1 is dispersed in 10 times its mass of deionized water, ultrasonically dispersed for 35 min at a power of 80 W, and a preset amount of Co-YPO4 complex and Ag-Cu auxiliary active components are added. The mixture is stirred at 65℃ for 5.5 h, evaporated and concentrated to dryness, and dried at 105℃ for 20 h to obtain the molecular sieve precursor.

[0068] S4. Hydrophobic modification: The molecular sieve precursor was dispersed in anhydrous ethanol at a ratio of 1 g of molecular sieve precursor to 25 mL of anhydrous ethanol. Polyvinylbenzene was added, and the mixture was ultrasonically dispersed for 22 min at 80 W. The mixture was then refluxed at 85 °C for 2.8 h. After cooling, the mixture was filtered, washed, and dried at 115 °C for 11 h to obtain a highly efficient and stable hydrophobic bifunctional catalyst.

[0069] Performance testing: The catalyst achieved an ethanol conversion rate of 85.3%, a butadiene selectivity of 78.1%, and a butadiene yield of 66.6%. After 185 hours of continuous operation, the catalytic activity retention rate was 95.5%. After six regeneration cycles, the catalytic activity did not decrease significantly.

[0070] Example 5 The efficient and stable hydrophobic bifunctional catalyst prepared in this embodiment has the following mass percentages: active component 15%, silane coupling agent KH-570 (hydrophobic modifier) ​​8%, and La-doped MFI hierarchical porous molecular sieve 77%. Among them, the mass ratio of Co-YPO4 complex to Ag-Cu co-active component (Ag:Cu=1:2) in the active component is 5:1; and the La element doping amount is 3% of the molecular sieve mass.

[0071] The specific preparation steps are as follows: S1. Preparation of La-doped MFI hierarchical porous molecular sieve: Tetraethyl orthosilicate, aluminum isopropoxide, lanthanum nitrate, tetrapropylammonium hydroxide, and deionized water were mixed in a molar ratio of Si:Al:La:template:H2O = 100:5:3:14:380 and stirred until homogeneous to form a gel. The gel was transferred to a hydrothermal reactor and hydrothermally crystallized at 175℃ for 34 h. After filtration and washing until neutral, the gel was dried at 115℃ for 14 h and calcined at 620℃ for 4.5 h to remove the template agent, thus obtaining the La-doped MFI hierarchical porous molecular sieve.

[0072] Nitrogen adsorption analysis revealed that its nitrogen adsorption-desorption curve exhibited a typical type IV isotherm with an H4 type hysteresis loop, indicating that the molecular sieve has a multi-level pore structure with both micropores and mesopores. Calculations showed that its specific surface area was 443 m² / g, with mesopore sizes mainly distributed in the range of 9–28 nm (average mesopore size 18.1 nm) and micropore sizes mainly distributed in the range of 0.56–0.88 nm (average micropore size 0.74 nm).

[0073] S2. Preparation of Co-YPO4 complex: Cobalt nitrate, yttrium nitrate and ammonium dihydrogen phosphate were dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.4:1.1. After stirring evenly, the pH was adjusted to 5.2, and the mixture was stirred at 75℃ for 2.5 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 140℃ for 9 h. After cooling, the mixture was filtered, washed, dried at 115℃ for 14 h, and calcined at 520℃ for 3.5 h to obtain the Co-YPO4 complex.

[0074] S3. Loading active components: The carrier prepared in step S1 is dispersed in 10 times its mass of deionized water, ultrasonically dispersed for 55 min at a power of 80 W, and a preset amount of Co-YPO4 complex and Ag-Cu auxiliary active components are added. The mixture is stirred at 75℃ for 4.5 h, evaporated and concentrated to dryness, and dried at 115℃ for 14 h to obtain the molecular sieve precursor.

[0075] S4. Hydrophobic modification: The molecular sieve precursor was dispersed in anhydrous ethanol at a ratio of 1 g of molecular sieve precursor to 25 mL of anhydrous ethanol. Silane coupling agent KH-570 was added, and the mixture was ultrasonically dispersed for 28 min at 80 W. The mixture was then refluxed at 95 °C for 2.2 h. After cooling, the mixture was filtered, washed, and dried at 125 °C for 9 h to obtain a highly efficient and stable hydrophobic bifunctional catalyst.

[0076] Performance testing: The catalyst achieved an ethanol conversion rate of 89.8%, a butadiene selectivity of 80.5%, and a butadiene yield of 72.3%. After continuous operation for 215 hours, the catalytic activity retention rate was 97.3%. After five regeneration cycles, the catalytic activity did not decrease significantly.

[0077] Example 6 The efficient and stable hydrophobic bifunctional catalyst prepared in this embodiment has the following mass percentages: active component 9%, polydivinylbenzene (hydrophobic modifier) ​​5%, and La-doped MFI hierarchical porous molecular sieve 86%; wherein, the mass ratio of Co-YPO4 complex to Ag co-active component in the active component is 4:1; and the La element doping amount is 1.5% of the molecular sieve mass.

[0078] The specific preparation steps are as follows: S1. Preparation of La-doped MFI hierarchical porous molecular sieve: Tetraethyl orthosilicate, aluminum isopropoxide, lanthanum nitrate, tetrapropylammonium hydroxide and deionized water were mixed in a molar ratio of Si:Al:La:template:H2O=100:3:1.5:13:340 and stirred until homogeneous to form a gel; the gel was transferred to a hydrothermal reactor and hydrothermally crystallized at 168℃ for 32h, filtered and washed until neutral, dried at 110℃ for 18h, calcined at 590℃ for 5h to remove the template agent, and the La-doped MFI hierarchical porous molecular sieve was obtained.

[0079] Nitrogen adsorption analysis revealed that its nitrogen adsorption-desorption curve exhibited a typical type IV isotherm with an H4 hysteresis loop, indicating that the molecular sieve has a multi-level pore structure with both micropores and mesopores. Calculations showed that its specific surface area was 405 m² / g, with mesopore sizes mainly distributed between 7–22 nm (average mesopore size 15.3 nm) and micropore sizes mainly distributed between 0.53–0.82 nm (average micropore size 0.69 nm).

[0080] S2. Preparation of Co-YPO4 complex: Cobalt nitrate, yttrium nitrate, and ammonium dihydrogen phosphate were dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.3:1.05. After stirring evenly, the pH was adjusted to 4.9, and the mixture was stirred at a constant temperature of 68℃ for 3.2 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 135℃ for 10 h. After cooling, the mixture was filtered, washed, dried at 110℃ for 18 h, and calcined at 490℃ for 4.2 h to obtain the Co-YPO4 complex.

[0081] S3. Loading active components: The carrier prepared in step S1 is dispersed in 10 times its mass of deionized water, ultrasonically dispersed for 40 min at a power of 80 W, and a preset amount of Co-YPO4 complex and Ag co-active components are added. The mixture is stirred at 68℃ for 5.2 h, evaporated and concentrated to dryness, and dried at 110℃ for 18 h to obtain the molecular sieve precursor.

[0082] S4. Hydrophobic modification: The molecular sieve precursor was dispersed in anhydrous ethanol at a ratio of 1 g: 25 mL, polydivinylbenzene was added, and the mixture was ultrasonically dispersed for 24 min at 80 W. The mixture was then refluxed at 88 °C for 2.6 h. After cooling, the mixture was filtered, washed, and dried at 118 °C for 10.5 h to obtain a highly efficient and stable hydrophobic bifunctional catalyst.

[0083] Performance testing: The catalyst achieved an ethanol conversion rate of 86.7%, a butadiene selectivity of 78.8%, and a butadiene yield of 68.3%. After 190 hours of continuous operation, the catalytic activity retention rate was 96.1%. After five regeneration cycles, the catalytic activity showed no significant decrease.

[0084] Example 7 The efficient and stable hydrophobic bifunctional catalyst prepared in this embodiment has the following mass percentages: active component 11%, silane coupling agent KH-570 (hydrophobic modifier) ​​5%, and La-doped MFI hierarchical porous molecular sieve 84%; wherein, the mass ratio of Co-YPO4 complex to Cu co-active component in the active component is 4:1; and the La element doping amount is 2.5% of the molecular sieve mass.

[0085] The specific preparation steps are as follows: S1. Preparation of La-doped MFI hierarchical porous molecular sieve: Tetraethyl orthosilicate, aluminum isopropoxide, lanthanum nitrate, tetrapropylammonium hydroxide, and deionized water were mixed in a molar ratio of Si:Al:La:template:H2O = 100:4:2.5:13:360 and stirred until homogeneous to form a gel. The gel was transferred to a hydrothermal reactor and hydrothermally crystallized at 172℃ for 29 h. After filtration and washing until neutral, the gel was dried at 112℃ for 16 h and calcined at 610℃ for 4.8 h to remove the template agent, thus obtaining the La-doped MFI hierarchical porous molecular sieve.

[0086] Nitrogen adsorption analysis revealed that its nitrogen adsorption-desorption curve exhibited a typical type IV isotherm with an H4 type hysteresis loop, indicating that the molecular sieve has a multi-level pore structure with both micropores and mesopores. Calculations showed that its specific surface area was 418 m² / g, with mesopore sizes mainly distributed in the range of 8–24 nm (average mesopore size 16.5 nm) and micropore sizes mainly distributed in the range of 0.54–0.84 nm (average micropore size 0.71 nm).

[0087] S2. Preparation of Co-YPO4 complex: Cobalt nitrate, yttrium nitrate, and ammonium dihydrogen phosphate were dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.4:1.15. After stirring evenly, the pH was adjusted to 5.3, and the mixture was stirred at 72℃ for 2.8 h. The mixture was then transferred to a hydrothermal reactor and hydrothermally reacted at 138℃ for 9.5 h. After cooling, the mixture was filtered, washed, dried at 112℃ for 16 h, and calcined at 510℃ for 3.8 h to obtain the Co-YPO4 complex.

[0088] S3. Loading active components: The carrier prepared in step S1 is dispersed in 10 times its mass of deionized water, ultrasonically dispersed for 50 min at a power of 80 W, and a preset amount of Co-YPO4 complex and Cu auxiliary active components are added. The mixture is stirred at 72℃ for 4.8 h, evaporated and concentrated to dryness, and dried at 112℃ for 16 h to obtain the molecular sieve precursor.

[0089] S4. Hydrophobic modification: The molecular sieve precursor was dispersed in anhydrous ethanol at a ratio of 1 g of molecular sieve precursor to 25 mL of anhydrous ethanol. Silane coupling agent KH-570 was added, and the mixture was ultrasonically dispersed for 26 min at 80 W. The mixture was then refluxed at 92 °C for 2.4 h. After cooling, the mixture was filtered, washed, and dried at 122 °C for 9.5 h to obtain a highly efficient and stable hydrophobic bifunctional catalyst.

[0090] Performance testing: The catalyst achieved an ethanol conversion rate of 88.9%, a butadiene selectivity of 79.8%, and a butadiene yield of 70.0%. After continuous operation for 205 hours, the catalytic activity retention rate was 96.8%. After five regeneration cycles, the catalytic activity did not decrease significantly.

[0091] Comparative Example 1 Using a conventional MgO / SiO2 catalyst (MgO loading 15%), the test was conducted under the same reaction conditions as in Example 1. The results were: ethanol conversion rate 68.3%, butadiene selectivity 58.7%, butadiene yield 40.1%. After continuous operation for 75 hours, the catalytic activity decreased to less than 50% of the initial activity and could not be used further. When using 70% aqueous ethanol directly, the ethanol conversion rate was only 40.2% and the butadiene selectivity was 45.3%.

[0092] Comparative Example 2 Using a Co-YPO4 bifunctional catalyst, the test was conducted under the same reaction conditions as in Example 1. The results were: ethanol conversion rate 79.5%, butadiene selectivity 69.2%, butadiene yield 55.0%. After continuous operation for 78 hours, the catalytic activity decreased to less than 50% of the initial activity. When using 70% aqueous ethanol directly, the ethanol conversion rate was 55.8% and the butadiene selectivity was 60.1%.

[0093] As can be seen from the comparison between Examples 1-7 and Comparative Examples 1-2, the efficient and stable hydrophobic bifunctional catalyst prepared by the present invention is significantly superior to existing catalysts in terms of catalytic activity, selectivity, stability and water resistance, regardless of the ratio of active components, the combination of co-active components and the adjustment of preparation parameters. It can effectively solve the core defects of the existing technology and has extremely high industrial application value.

[0094] Comparative Example 3 The catalyst prepared in this comparative example is completely consistent with the mass percentage of each component and the preparation steps in Example 1, except that the hydrophobic modification step S4 is omitted. That is, the molecular sieve precursor obtained after loading the active component is directly dried at 120°C for 10 h to obtain the catalyst without hydrophobic modification.

[0095] Performance testing: Tests were conducted under the same reaction conditions as in Example 1. The results were as follows: ethanol conversion rate 72.5%, butadiene selectivity 67.3%, butadiene yield 48.8%. After continuous operation for 65 hours, the catalytic activity decreased to less than 50% of the initial activity and could not be used further. When 70% aqueous ethanol was used directly, the ethanol conversion rate was only 48.3% and the butadiene selectivity was 52.1%. Significant carbon deposits appeared on the catalyst surface, and the active sites were severely poisoned by water molecules.

[0096] Comparative Example 4 The catalyst prepared in this comparative example is completely consistent with the mass percentage of each component and the preparation steps in Example 3, except that the hydrophobic modification step S4 is omitted. That is, the molecular sieve precursor obtained after loading the active component is directly dried at 130°C for 8 hours to obtain the catalyst without hydrophobic modification.

[0097] Performance testing: Tests were conducted under the same reaction conditions as in Example 3. The results were as follows: ethanol conversion rate 75.8%, butadiene selectivity 69.5%, butadiene yield 52.7%. After continuous operation for 70 hours, the catalytic activity decreased to less than 50% of the initial activity. When 70% aqueous ethanol was used directly, the ethanol conversion rate was 51.6%, the butadiene selectivity was 55.8%, and significant water and carbon accumulation appeared in the catalyst channels, with slight loss of active components.

[0098] A comparison of Examples 1-7 with Comparative Examples 3-4 shows that the highly efficient and stable hydrophobic bifunctional catalyst prepared by the present invention, through the introduction of a hydrophobic modification step, can significantly improve the catalyst's water resistance, anti-carbon deposition ability, and stability, solving the defects of easy activity decline and deactivation of unmodified catalysts. At the same time, hydrophobic modification can also indirectly improve catalytic activity and butadiene selectivity, fully demonstrating the core role of hydrophobic modification in the catalyst of the present invention, further highlighting the innovation and practicality of the present invention.

[0099] Figure 1-4The figures show the chromatograms of the raw material ethanol, the target product butadiene, the gas phase product of the reaction in Example 1, and the liquid phase product of the reaction in Example 1, respectively. The figures show... Figure 1 The chromatogram of the raw material ethanol showed no obvious impurity peaks, indicating that the purity of the raw material met the requirements. Figure 2 The sharp and high proportion of butadiene chromatographic peaks corroborate the excellent selectivity of the catalyst for butadiene. Figure 3 The low content of byproducts in the gas phase products demonstrates the advantage of catalysts in suppressing side reactions; Figure 4 The presence of trace amounts of polar byproducts in the liquid phase products indicates that the catalyst is resistant to carbon deposition and has strong stability.

[0100] The specific gas chromatography conditions were as follows: instrument model: Fuli F70; column RB-PLOT Q 30m×0.53mm×15μm, detector FID, injection volume XμL, split ratio 30:1, run time 30 min, initial temperature 40℃, hold for 5 min, increase to 60℃ at 5℃ / min, hold for 1 min, increase to 230℃ at 10℃ / min, hold for 3 min, air flow rate 300 mL / min, hydrogen flow rate 30 mL / min, argon flow rate 158 mL / min.

[0101] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A highly efficient and stable hydrophobic bifunctional catalyst, characterized in that, The catalyst is a rare earth metal-modified hydrophobic bifunctional molecular sieve catalyst, using a La-doped MFI hierarchical porous molecular sieve as a support, and loading active components and hydrophobic modifiers. The components, by mass percentage, are: active components 5-15%, hydrophobic modifiers 2-8%, and La-doped MFI hierarchical porous molecular sieves 77-93%. The active component consists of a main active component and a co-active component. The main active component is a Co-YPO4 complex, and the co-active component is one or two of Ag and Cu mixed in any proportion. The mass ratio of the main active component to the co-active component is 3-5:

1. The hydrophobic modifier is polyvinylbenzene or silane coupling agent KH-570.

2. The highly efficient and stable hydrophobic bifunctional catalyst according to claim 1, characterized in that, The La-doped MFI hierarchical porous molecular sieve has a microporous-mesoporous coexistence structure with a specific surface area of ​​350-550 m². 2 / g, with mesopore size of 2-50nm and micropore size of 0.5-1.0nm; the doping amount of La element is 1-3% of the molecular sieve mass.

3. The highly efficient and stable hydrophobic bifunctional catalyst according to claim 1, characterized in that, The preparation method of the Co-YPO4 complex is as follows: Cobalt nitrate, yttrium nitrate and ammonium dihydrogen phosphate are dissolved in deionized water at a molar ratio of Co:Y:P = 1:1.2-1.5:1.0-1.

2. After stirring evenly, the pH is adjusted to 4.5-5.5, and the mixture is stirred at a constant temperature of 60-80℃ for 2-4 hours. The mixture is then transferred to a hydrothermal reactor and hydrothermally reacted at 120-150℃ for 8-12 hours. After cooling, filtration, washing, and drying, the mixture is calcined at 450-550℃ for 3-5 hours to obtain the Co-YPO4 complex.

4. A method for preparing the highly efficient and stable hydrophobic bifunctional catalyst as described in claim 1, characterized in that, Specifically, the steps include the following: S1, Preparation of La-doped MFI hierarchical porous molecular sieve: Silicon source, aluminum source, La source, template agent and deionized water are mixed and stirred to form a gel. The gel is then hydrothermally crystallized, filtered, washed, dried and calcined to obtain La-doped MFI hierarchical porous molecular sieve. S2, Loading active components: The La-doped MFI hierarchical porous molecular sieve prepared in step S1 is dispersed in deionized water, ultrasonically dispersed, the main active component Co-YPO4 complex and the auxiliary active component are added, stirred at constant temperature, evaporated and concentrated to dry, and dried to obtain the molecular sieve precursor. S3. Hydrophobic modification: The molecular sieve precursor obtained in step S2 is dispersed in anhydrous ethanol, a hydrophobic modifier is added, ultrasonically dispersed, refluxed, cooled, filtered, washed and dried to obtain the highly efficient and stable hydrophobic bifunctional catalyst.

5. The preparation method according to claim 4, characterized in that, The silicon source mentioned in step S1 is tetraethyl orthosilicate, the aluminum source is aluminum isopropoxide, the La source is lanthanum nitrate, and the template agent is tetrapropylammonium hydroxide; The molar ratio of the silicon source, aluminum source, La source, template agent, and deionized water is Si:Al:La:template agent:H2O = 100:2-5:1-3:10-15:300-400; The hydrothermal crystallization temperature is 160-180℃, and the time is 24-36h; The drying temperature is 100-120℃, and the time is 12-24h; The roasting temperature is 550-650℃, and the time is 4-6 hours.

6. The preparation method according to claim 4, characterized in that, The deionized water mentioned in step S2 is 10-15 times the mass of the La-doped MFI hierarchical porous molecular sieve. The ultrasonic dispersion time is 30-60 min, and the power is 80 W. The constant temperature stirring temperature is 60-80℃, and the time is 4-6 hours; The drying temperature is 100-120℃, and the time is 12-24h.

7. The preparation method according to claim 4, characterized in that, The ratio of the molecular sieve precursor mass to the volume of anhydrous ethanol in step S3 is 1g: 20-30mL; The ultrasonic dispersion time is 20-30 minutes, and the power is 80W. The reflux reaction temperature is 80-100℃, and the time is 2-3 hours; The drying temperature is 110-130℃, and the time is 8-12 hours.

8. The application of a highly efficient, stable, hydrophobic bifunctional catalyst as described in claim 1 or a highly efficient, stable, hydrophobic bifunctional catalyst prepared by the method described in claim 4 in the catalytic reaction of one-step preparation of butadiene from bioethanol.

9. The application according to claim 8, characterized in that, The aforementioned highly efficient, stable, hydrophobic bifunctional catalyst can directly catalyze the conversion of 60-80% (w / w) aqueous ethanol, at a reaction temperature of 280-320℃, a reaction pressure of 0.3-0.6 MPa, and a feed mass hourly space velocity of 0.8-1.5 h⁻¹. -1 The volume ratio of raw gas to nitrogen is 1:3.

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