Catalyst and method for preparing C4 < + > oxygen-containing compound through ethanol grading relay

Abstract

The invention provides a catalyst and a method for preparing a C4 < + > oxygen-containing compound through ethanol grading relay. According to the catalyst, an ethanol dehydrogenation catalyst and an aldol condensation catalyst are synergistically combined into a graded catalytic system and are used for respectively and independently catalyzing ethanol dehydrogenation reaction and aldol condensation reaction, so that the flexible control of the reaction process is realized, and the mutual restriction of active sites is avoided; ethanol can be converted into C4 + oxygen-containing compounds with high selectivity and high conversion rate under mild conditions, and meanwhile side reactions and generation of by-products are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical catalysis, and particularly relates to a catalyst and a method for preparing C4+ oxygenates by ethanol staged relay. Background Art

[0002] C4+ oxygenates include fatty alcohols and aromatic alcohols / aldehydes, which are important bulk chemical raw materials. They can be used to prepare plasticizers, lubricating oils, and are also widely used in the fields of cosmetics, medicine, biofuels, and energy storage. Industrially, the hydroformylation method is used to prepare fatty alcohols, mainly using propylene, carbon monoxide, and hydrogen as raw materials, and fatty alcohols are produced through carbonylation and hydrogenation processes. There is also the method of preparing aromatic alcohols / aldehydes by oxidizing xylene, which uses xylene as the raw material and undergoes a pressurized oxidation reaction in air. The raw materials for the industrial production of C4+ oxygenates highly depend on non-renewable petroleum resources, so it is necessary to develop a route for preparing C4+ oxygenates using alternative resources as raw materials.

[0003] Ethanol is the most widely used renewable energy source in the world, and its sources are abundant, including bioethanol and coal-based ethanol. Bioethanol includes first-generation bioethanol prepared from starches such as corn and sucrose and second-generation bioethanol prepared from lignocellulose. In 2023, the global production of biofuel ethanol reached 88.97 million tons, and the production of biofuel ethanol in China was approximately 2.7 million tons; China has rich coal resources, wide distribution, complete coal types, and sufficient raw materials. Coal-based ethanol is prepared from coal, and in 2022, the production capacity of coal-based ethanol in China has reached 1.055 million tons. As an important platform molecule, ethanol can be used to produce a series of high-value chemicals by site-specific activation of its various chemical bonds. High-value fine chemicals such as acetaldehyde and butyraldehyde can be prepared by dehydrogenation, and acetaldehyde can be further prepared to produce C4+ oxygenates through condensation and other steps, such as high-value products like n-butanol, n-hexanol, n-octanol, and aromatic alcohols / aldehydes. Due to the advantages of abundant sources and large production of ethanol, a route for preparing C4+ oxygenates using ethanol as the raw material has been proposed.

[0004] Currently, there are already some studies on the preparation of C 4+Research on oxygen-containing compounds. For example, the Milstein research group used a pincer ruthenium complex as a catalyst and sodium ethoxide as a strong base to catalyze the reaction of ethanol at 150 °C, with an ethanol conversion rate as high as 73.4% and a selectivity for C4+ alcohols >99%. The Mg-Al composite oxide prepared by the Appel research group with an Mg / Al ratio of 3:1 had the best reaction performance at 350 °C and 0.1 MPa N2, with an ethanol conversion rate of 33% and a selectivity for C4+ alcohols of 55%. The Lu Anhui research group loaded Cu nanoparticles (Cu-HAP) on hydroxyapatite, and obtained an ethanol conversion rate of 36.6% and a selectivity for C4+ alcohols of 86.7% at 250 °C and 0.1 MPa H2; at 250 °C and 0.1 MPa N2, the ethanol conversion rate was 9% and the selectivity for aromatic alcohols / aldehydes was 46.1%. At the same time, this research group used a cobalt-hydroxyapatite catalyst (Co-HAP) to directly catalyze ethanol to produce the aromatic product methylbenzyl alcohol, and obtained an ethanol conversion rate of 35% and a selectivity for 2-methylbenzyl alcohol of 54% at 325 °C. The Flaherty research group used hydroxyapatite as a catalyst and fed a mixture of acetaldehyde-ethanol (acetaldehyde / ethanol = 1 / 3), and obtained an acetaldehyde conversion rate of 55% and a selectivity for aromatic compounds of 33% (ACS Catal. 2016, 6, 7278).

[0005] In the above preparation methods, the preparation of C4+ oxygen-containing compounds from ethanol involves multiple catalytic processes such as direct dehydrogenation of ethanol, aldol condensation, and hydrogen transfer hydrogenation. There is a problem of mutual restriction of active sites, resulting in generally low yields of C4+ oxygen-containing compounds and easy occurrence of dehydration reactions to produce other by-products. Therefore, how to achieve flexible control of the reaction process in view of the objective situation of mutual restriction of active sites is an urgent problem to be solved at present. Summary of the Invention

[0006] To solve the above problems, the present invention provides a catalyst and method for the stepwise relay preparation of C4+ oxygen-containing compounds from ethanol.

[0007] The catalyst consists of an ethanol dehydrogenation catalyst and an aldol condensation catalyst that are synergistically combined to form a hierarchical catalytic system, independently catalyzing the ethanol dehydrogenation reaction and the aldol condensation reaction, respectively, so as to achieve flexible control of the reaction process, avoid mutual restriction of active sites, and be able to convert ethanol into C4+ oxygen-containing compounds with high selectivity and high conversion rate under mild conditions, while reducing the generation of side reactions and by-products.

[0008] The technical solution of the present invention is as follows: The present invention provides a catalyst for the stepwise relay preparation of C4+ oxygen-containing compounds from ethanol, and the catalyst includes an ethanol dehydrogenation catalyst and an aldol condensation catalyst, The active metal of the ethanol dehydrogenation catalyst is selected from at least one of Cu, Ni, Co, Ag, Pd, Rh, Ru, Pt, Ir, and Zn, and the carrier of the ethanol dehydrogenation catalyst is a metal oxide, selected from at least one of SiO2, ZnO, MnOx (where the range of x is 1-14), and TiO2; wherein, the molar ratio of the metal oxide to the active metal is (0.1~5.0):1; The aldol condensation catalyst is MgAlX-LDO, and X is selected from at least one of Cu, Zn, Ni, Ru, Ag, Co, La, and Zr; wherein, the molar ratio of Mg to Al+X is (1~5):1, and the molar ratio of X to Al is (0.01~1.0):1; Wherein, the mass ratio of the ethanol dehydrogenation catalyst to the aldol condensation catalyst is 1:(5~20).

[0009] Further, the ethanol dehydrogenation catalyst is 20-40 mesh particles obtained by tabletting, granulating, and sieving; the aldol condensation catalyst is 20-40 mesh particles obtained by tabletting, granulating, and sieving.

[0010] Further, the ethanol dehydrogenation catalyst and the aldol condensation catalyst are 20~40 mesh particles obtained by physical mixing and granulating.

[0011] Further, the ethanol dehydrogenation catalyst and the aldol condensation catalyst are 20-40 mesh particles obtained by physical mixing, pulverizing, and granulating.

[0012] Further preferably, the mass ratio of the ethanol dehydrogenation catalyst to the aldol condensation catalyst is 1:(9~12).

[0013] Further preferably, in the aldol condensation catalyst, the molar ratio of X to Al is 0.15:0.85, 0.1:0.9, or 0.05:0.95.

[0014] Further preferably, the catalyst includes Cu / ZnO and MgAlLa-LDO, wherein the molar ratio of ZnO to Cu is Cu / ZnO = 1:1, and the molar ratio of Mg, Al, and X is Mg / Al / X = 1:0.9:0.1.

[0015] Further, the preparation method of the ethanol dehydrogenation catalyst is as follows: Step T1: Prepare an active metal organic framework product Add metal oxide to DMF and stir ultrasonically to obtain a suspension, denoted as Solution A. The molar ratio of metal oxide to DMF is (0.01 - 1):1; Prepare a salt solution of the active component, denoted as Solution B, with a concentration of 0.2 - 0.8 mol / L; Prepare an alcohol solution of trimesic acid, denoted as Solution C, with a concentration of 0.1 - 1.0 mol / L; Mix Solution A, Solution B, and Solution C at 30 - 80 °C, stir, and then let stand for 1 - 10 h. Centrifuge to obtain a solid. Wash the obtained solid and place it in an oven at 60 - 80 °C for drying for 1 - 24 h to obtain an active metal-organic framework product; In Step T2: Calcination reaction Place the active metal-organic framework obtained in Step T1 in a porcelain boat and calcine it at 200 - 700 °C for 0.5 - 6 h to obtain a catalyst precursor; In Step T3: Hydrogen reduction Place the catalyst precursor obtained in Step T2 in a porcelain boat and reduce it in a hydrogen atmosphere at 100 - 500 °C for 0.1 - 4 h to obtain an ethanol dehydrogenation catalyst.

[0016] Furthermore, in Step T1, the solvent is DMF.

[0017] Furthermore, in Step T1, the molar ratio of the metal oxide, the active metal, and trimesic acid is (0.1 - 5.0):1:1.5.

[0018] Furthermore, in Step T1, the salt solution of the active metal includes one or more combinations of chloride, acetate, sulfate, and nitrate of the active metal.

[0019] Furthermore, in Step T1, the solid is washed 3 - 4 times.

[0020] Furthermore, in Step T3, the concentration of the hydrogen atmosphere is at least one of H2 / Ar, H2 / He, H2 / N2 with a concentration of 5 - 100 vol%. Among them, gases such as Ar, He, and N2 mainly play a role in diluting hydrogen and providing an inert atmosphere to prevent overreaction or other side reactions during the reduction process, and also help to control the reaction rate and temperature distribution.

[0021] In the preparation process of the ethanol dehydrogenation catalyst of the present invention, first, when solution A, solution B, and solution C are mixed and stirred at 30-80°C, the active metal ions react with the carboxyl groups in trimesic acid (organic ligands) to form an active metal organic framework product (MOF) with a specific structure and function through covalent bonds and coordination bonds. Then, the MOF undergoes a calcination process at 200-700°C, and the organic ligands (trimesic acid) in the MOF structure undergo thermal decomposition and volatilize in the form of carbon dioxide and water. During this calcination process, the active metal ions undergo oxidation state adjustment and rearrangement at high temperature, and interact with the metal oxide carrier, so that the active metal ions are better dispersed on the surface of the metal oxide carrier or enter its lattice, forming a catalyst precursor with a specific structure and active sites, preparing for the subsequent reduction process. Finally, during the reduction process, hydrogen acts as a reducing agent and undergoes a redox reaction with the active metal oxide in the catalyst precursor. The hydrogen atoms in the hydrogen will capture the oxygen atoms in the active metal oxide, reducing the active metal ions from a higher oxidation state to a lower oxidation state or even a metal element state; the reduced active metal is loaded on the metal oxide carrier in a highly dispersed form to form a metal catalyst loaded with a metal oxide having catalytic activity.

[0022] Furthermore, the preparation method of the aldol condensation catalyst is as follows: Step S1: Precipitation and crystallization The metal Mg, metal Al and metal X are respectively prepared into corresponding metal salt solutions, and the concentration of each metal salt solution is controlled to be 0.1-1.0 mol / L; sodium hydroxide and anhydrous sodium carbonate are added into water to prepare an alkaline solution with a concentration of 0.1-10 mM.

[0023] Mix the metal salt solutions and the alkali solution under sufficient stirring and let stand at 30-100°C for 1-24 hours; The obtained solid is washed 2 to 5 times and baked for 1 to 24 hours to obtain a catalyst precursor; Step S2: Calcination reaction The catalyst precursor obtained in step S1 is placed in a porcelain boat and calcined at 400-700° C. for 0.5-6 h to obtain MgAlX-LDO, i.e., the aldol condensation catalyst.

[0024] Furthermore, in step S1, X is selected from at least one of Cu, Zn, Ni, Ru, Ag, Co, La, and Zr; wherein the molar ratio of Mg to Al+X is (1-5): 1, and the molar ratio of X to Al is = (0.01-1.0): 1.

[0025] Further preferably, in step S1, the molar ratio of Mg, Al and X is 1:(0.85 - 0.95):(0.05 - 0.15).

[0026] Further, in step S1, the metal salt is selected from one or more combinations of chlorides, acetates, sulfates, and nitrates.

[0027] Further, in step S1, the molar ratio of sodium hydroxide to anhydrous sodium carbonate is (1 - 5):1.

[0028] Further, in step S1, the molar ratio of each metal salt solution to the alkali solution is (1 - 5):1.

[0029] Further, in step S1, the temperature for baking the solid is 65°C.

[0030] Further preferably, the aldol condensation catalyst is at least one of MgAl 0.95 La 0.05 -LDO, MgAl 0.9 La 0.1 -LDO, MgAl 0.85 La 0.15 -LDO.

[0031] In the preparation process of the aldol condensation catalyst of the present invention, first, the salt solution and the alkali solution are mixed under sufficient stirring, and metal ions react with anions such as OH⁻ and CO3 2- to form insoluble substances such as metal hydroxides or carbonates, which precipitate. The mixture is left to stand at 30 - 100°C for 1 - 24 h, and the precipitate will undergo a crystallization process, causing the formed precipitate particles to gradually grow and form a substance with a certain crystal structure and morphology, which is beneficial for subsequent separation and treatment. Then, the obtained catalyst precursor is calcined at 300 - 800°C for 0.5 - 6 h. During the high-temperature calcination process, the metal hydroxide will undergo a decomposition reaction, losing crystal water and transforming into a metal oxide. At the same time, different metal oxides may interact with each other to form a composite oxide structure, thereby obtaining a metal composite oxide with certain catalytic performance as the aldol condensation catalyst.

[0032] The present invention also provides a method for preparing oxygen-containing compounds by ethanol fractional relay, the method comprising the following steps: 4+ Step 1: Load the ethanol dehydrogenation catalyst and the aldol condensation catalyst into a reaction tube, and install the reaction tube into a fixed-bed reactor; Step 2: Heat-treat the loaded catalyst at 300 - 400 °C in a hydrogen or inert gas atmosphere for 0.5 - 3 h; then vaporize ethanol and mix it with other inert gases and introduce them into the above fixed-bed reactor, and carry out a catalytic reaction at 120 °C - 480 °C and a pressure of 1 - 100 atm to generate C 4+ oxygenated compounds.

[0033] Further, in Step 1, the mass ratio of the ethanol dehydrogenation catalyst to the aldol condensation catalyst is 1:(5 - 20), preferably 1:(9 - 12).

[0034] Further, in Step 1, the ethanol dehydrogenation catalyst and the aldol condensation catalyst in the reaction tube are in a double-bed layer structure or a single-bed layer structure.

[0035] Further, in Step 1, the ethanol dehydrogenation catalyst and the aldol condensation catalyst are each made into particles of 20 - 40 mesh through tabletting, granulation, and sieving, and then filled into the reaction tube in sequence to form a double-bed layer structure.

[0036] Further, in the double-bed layer structure, the ethanol dehydrogenation catalyst and the aldol condensation catalyst are filled into the reaction tube in sequence, and the reaction tube is filled with quartz sand.

[0037] Further, in Step 1, the ethanol dehydrogenation catalyst and the aldol condensation catalyst are made into particles of 20 - 40 mesh through physical mixing and granulation, and then evenly mixed and filled into the reaction tube to form a single-bed layer structure.

[0038] Further, in Step 1, the ethanol dehydrogenation catalyst and the aldol condensation catalyst are made into particles of (20 - 40) mesh through physical mixing, crushing, and granulation, and then evenly mixed and filled into the reaction tube to form a single-bed layer structure.

[0039] Further, in Step 1, install the reaction tube into the fixed-bed reactor and check for leaks with N2.

[0040] Further, in Step 2, ethanol is pumped into a vaporization chamber at 200 °C at a flow rate of 0.4 - 20.0 mL / h for vaporization.

[0041] Further, in Step 2, the flow rate of the inert gas is set to 20 - 200 mL / min.

[0042] In Step 2, after ethanol is vaporized, it is mixed with other gases. Among them, ethanol is used as a reactant, and an inert gas such as N2 is used as a carrier. By adjusting the flow rate of ethanol, the partial pressure of ethanol, that is, the reaction concentration, can be adjusted.

[0043] Further, in step 2, the inert atmosphere includes at least one of Ar, N2, and He.

[0044] Further, the ethanol conversion rate is 70-85%, and the selectivity of oxygenates is 82-95%. 4+ The selectivity of oxygenates is 82-95%.

[0045] The beneficial effects of the present invention are as follows: (1) Raw material advantages and economic feasibility: Compared with the traditional process for preparing oxygenates using petroleum as a raw material, the present invention uses ethanol as a raw material, which has a greater cost advantage in the raw material procurement and supply links, can effectively reduce production costs, and improve the economic benefits and market competitiveness of enterprises. 4+ Compared with the traditional process for preparing oxygenates using petroleum as a raw material, the present invention uses ethanol as a raw material, which has a greater cost advantage in the raw material procurement and supply links, can effectively reduce production costs, and improve the economic benefits and market competitiveness of enterprises.

[0046] (2) Excellent performance of hierarchical relay catalysis: The present invention adopts hierarchical relay catalysis of ethanol dehydrogenation and aldol condensation reaction active sites. This unique catalytic method solves the problem of mutual restriction of active sites in traditional methods and realizes flexible control of the reaction process by precisely controlling the reaction steps.

[0047] On the one hand, through hierarchical relay catalysis, the present invention effectively reduces the occurrence of dehydration reactions, makes the reaction system purer, reduces the difficulty of subsequent product separation and purification, and further saves production costs.

[0048] On the other hand, high conversion rate of ethanol and high selectivity of oxygenates are achieved. Experimental data show that the ethanol conversion rate is as high as 82%, and the selectivity of oxygenates is as high as 91%. Compared with the prior art, the production efficiency and product quality are greatly improved, providing higher economic benefits for industrial production. 4+ On the other hand, high conversion rate of ethanol and high selectivity of oxygenates are achieved. Experimental data show that the ethanol conversion rate is as high as 82%, and the selectivity of oxygenates is as high as 91%. Compared with the prior art, the production efficiency and product quality are greatly improved, providing higher economic benefits for industrial production. 4+ On the other hand, high conversion rate of ethanol and high selectivity of oxygenates are achieved. Experimental data show that the ethanol conversion rate is as high as 82%, and the selectivity of oxygenates is as high as 91%. Compared with the prior art, the production efficiency and product quality are greatly improved, providing higher economic benefits for industrial production.

[0049] (3) Advantages of mild reaction conditions: The reaction for preparing oxygenates by catalyzing ethanol in the present invention has mild reaction conditions and can be carried out only under normal pressure and within the temperature range of 150-300 °C. The mild reaction conditions reduce the requirements for reaction equipment, reduce the investment cost and maintenance cost of equipment. At the same time, it also reduces energy consumption, which is in line with the concept of green chemistry and sustainable development today. In addition, reacting under mild conditions can improve the safety of the reaction process and reduce potential safety risks brought by high temperature and high pressure. 4+ The reaction for preparing oxygenates by catalyzing ethanol in the present invention has mild reaction conditions and can be carried out only under normal pressure and within the temperature range of 150-300 °C. The mild reaction conditions reduce the requirements for reaction equipment, reduce the investment cost and maintenance cost of equipment. At the same time, it also reduces energy consumption, which is in line with the concept of green chemistry and sustainable development today. In addition, reacting under mild conditions can improve the safety of the reaction process and reduce potential safety risks brought by high temperature and high pressure.

[0050] (4) Product separation and industrialization prospects: In C 4+In the oxygenated compound products, fatty alcohols / aldehydes and aromatic compounds are easily separated by distillation, with low operating costs, enabling efficient separation and purification of the products, and having broad prospects for industrial application. Description of the Drawings

[0051] Figure 1 It is the XRD pattern of the Cu / ZnO catalyst in the preparation example; Figure 2 It is the XRD pattern of the MgAlLa-LDO catalyst in the preparation example; Figure 3 It is a schematic diagram of different catalyst loading methods in Example 1; Figure 4 It is for the product distribution diagram of oxygenated compounds prepared by catalytic ethanol staged relay using a dual-bed layer loading of ethanol dehydrogenation catalyst and aldol condensation catalyst in Example 1 4+ Product distribution diagram of oxygenated compounds. Detailed Description of the Invention

[0052] The following provides a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0053] Preparation Example 1 (Cu / ZnO) Preparation process of Cu / ZnO: Step T1: Preparation of active metal-organic framework product Add ZnO to the DMF solution and stir ultrasonically to obtain solution A, with the molar ratio of metal oxide to DMF being 0.02:1; prepare a Cu(NO3)2 solution with a molar concentration of 0.5 mol / L, denoted as solution B; prepare a trimesic acid ethanol solution with a concentration of 0.2 mol / L, denoted as solution C; Mix solution A, solution B, and solution C at 30°C, stir, and then let stand for 2 h. Centrifuge to obtain a solid, wash the obtained solid 3 - 4 times, place it in an 80°C oven and dry for 12 h to obtain the active metal-organic framework product; In step T2: Calcination reaction Calcine the active metal-organic framework obtained in step T1 at 400°C for 4 h to obtain the catalyst precursor; In step T3: Hydrogen reduction Place the catalyst precursor obtained in step T2 in a porcelain boat and reduce it in a hydrogen atmosphere at 350°C for 1 h to obtain Cu / ZnO.

[0054] As Figure 1 shown in the XRD pattern of the Cu / ZnO catalyst, characteristic peaks exist at about 2θ = 43.2° and 50.5°, which are respectively attributed to the characteristic diffraction peaks of (111) and (220) of Cu.

[0055] Preparation Example 2 (MgAlLa-LDO) Preparation process of MgAlLa-LDO:[[]] Step S1: Precipitation and crystallization Dissolve Mg(NO3)2, Al(NO3)3, and La(NO3)3 salts in an aqueous solution, and the molar concentration of each metal salt solution is 0.3 mol / L; add sodium hydroxide and anhydrous sodium carbonate to water to prepare an alkali solution with a concentration of 0.75 mol / L, where the molar ratio of sodium hydroxide to anhydrous sodium carbonate is 4:1; The molar ratio of each metal salt solution to the alkali solution is 1:1; Mix each salt solution and the alkali solution under sufficient stirring and then perform static crystallization at 65 °C for 10 - 18 h; Wash the obtained solid 2 - 5 times, place it in an oven and dry it for 12 h to obtain a catalyst precursor; Step S2: Calcination reaction Place the catalyst precursor obtained in Step S1 in a porcelain boat and calcine it at 600 °C for 0.5 - 6 h to obtain the metal composite oxide MgAlLa-LDO, that is, the aldol condensation catalyst.

[0056] As shown in the XRD pattern of MgAlLa-LDO in Figure 2, characteristic peaks exist at around 2θ = 42.9° and 62.3°, which respectively belong to the characteristic diffraction peaks of (200) and (220) of MgO.

[0057] In the above method, by controlling the mass ratio of aluminum nitrate and lanthanum nitrate added, the ratio of Al and La can be adjusted to obtain three aldol condensation catalysts, namely MgAl 0.95 La 0.05 -LDO, MgAl 0.9 La 0.1 -LDO, MgAl 0.85 La 0.15 -LDO.

[0058] Example 1 Method for preparing oxygen-containing compounds by ethanol fractional relay, as 4+ shown in (1), adopt a double-bed layer to sequentially load an ethanol dehydrogenation catalyst and an aldol condensation catalyst, and the reactant first acts with the ethanol dehydrogenation catalyst and then with the aldol condensation catalyst. Figure 3 The steps are as follows: Step 1: The ethanol dehydrogenation catalyst Cu / ZnO and the aldol condensation catalyst MgAl obtained in the preparation example 0.9 La 0.1- The LDOs are each pressed into tablets of a certain thickness using a tableting machine, granulated, and sieved to obtain particles with a mesh size of 20 - 40. Then, they are filled into the isothermal zone of a reaction tube in a mass ratio of 1:9 in sequence, and the remaining part of the reaction tube is filled with quartz sand of 20 - 40 mesh. The reaction tube is installed on a micro fixed-bed reaction device and leak-tested with N2; Step 2: Pretreat the catalyst on the micro fixed-bed device at 300 - 400 °C for 1 h under a hydrogen atmosphere; after pretreatment, control the temperature at 300 °C and mix and introduce N2 and ethanol vapor. The flow rate of N2 is set at 40 mL / min, and chromatographically pure ethanol is pumped into a 200 °C vaporization chamber at a flow rate of 0.4 mL / h using a liquid injection pump for vaporization to generate C 4+ oxygenates.

[0059] The products are analyzed using an on-line chromatograph. The ethanol conversion rate is 80%, and the selectivity of C 4+ oxygenates is 82%.

[0060] A method for catalytically preparing C 4+ oxygenates by staged relay of ethanol using a dual-bed packing of an ethanol dehydrogenation catalyst and an aldol condensation catalyst. The product distribution diagram of the C 4+ oxygenates is shown in Figure 4. The dual-bed catalytic system can achieve a high ethanol conversion rate while avoiding the dehydration reaction of ethanol, resulting in a selectivity of C

[0061] Example 2 A method for preparing C 4+ oxygenates by staged relay of ethanol, as Figure 3 shown in (2), in which a particle mixture of an ethanol dehydrogenation catalyst and an aldol condensation catalyst is packed in a single bed.

[0062] The steps are as follows: Step 1: Physically mix the ethanol dehydrogenation catalyst Cu / ZnO and the aldol condensation catalyst MgAl 0.9 La 0.1 -LDO obtained in the preparation example in a mass ratio of 1:9, granulate to obtain particles with a mesh size of 20 - 40, place them in the isothermal zone of a reaction tube, and fill the remaining part of the reaction tube with quartz sand of 20 - 40 mesh. The reaction tube is installed on a micro fixed-bed reaction device and leak-tested with N2; Step 2: Pretreat the catalyst on the micro fixed-bed device at 300 - 400 °C for 1 h under a hydrogen atmosphere; after pretreatment, control the temperature at 300 °C and mix and introduce N2 and ethanol vapor. The flow rate of N2 is set at 40 mL / min, and chromatographically pure ethanol is pumped into a 200 °C vaporization chamber at a flow rate of 0.4 mL / h using a liquid injection pump for vaporization to generate C 4+Oxygenated compounds.

[0063] The product was analyzed by on-line chromatography. The ethanol conversion rate was 30%, and the selectivity of C 4+ oxygenated compounds was 71%.

[0064] Example 3 Method for preparing C oxygenated compounds by ethanol staged relay, as 4+ shown in (3), in which a powder mixture of an ethanol dehydrogenation catalyst and an aldol condensation catalyst is loaded in a single bed layer. Figure 3 The steps are as follows:

[0065] Step 1: Physically mix, crush, and granulate the ethanol dehydrogenation catalyst Cu / ZnO and the aldol condensation catalyst MgAl La 0.9 La 0.1 -LDO obtained in the preparation example according to a mass ratio of 1:9 to obtain a powder of 20-40 mesh, and then place it in the constant temperature area of a reaction tube, and fill the rest of the reaction tube with 20-40 mesh quartz sand. Install the reaction tube on a micro fixed bed reaction device and leak test it with N2; Step 2: Pretreat the catalyst at 300-400 °C for 1 h on the micro fixed bed device, and the treatment atmosphere is hydrogen; after pretreatment, control the temperature at 300 °C and mix and introduce N2 and ethanol vapor. The flow rate of N2 is set at 40 mL / min, and chromatographically pure ethanol is pumped into the vaporization chamber at 200 °C at a flow rate of 0.4 mL / h by a liquid injection pump for vaporization to generate C 4+ oxygenated compounds.

[0066] The product was analyzed by on-line chromatography. The ethanol conversion rate was 20%, and the selectivity of C 4+ oxygenated compounds was 47%.

[0067] Comparative Example 1 Different from the double-bed layer loading method of the catalyst in Example 1, as Figure 3 shown in (4), first load the aldol condensation catalyst MgAlLa-LDO, and then load the ethanol dehydrogenation catalyst Cu / ZnO.

[0068] The steps are as follows: Step 1: Press the ethanol dehydrogenation catalyst Cu / ZnO and the aldol condensation catalyst MgAl 0.9 La 0.1 -LDO obtained in the preparation example into tablets of a certain thickness respectively, then granulate and screen them to obtain 20-40 mesh particles, and then load them according to a mass ratio of 1:9. First load the aldol condensation catalyst MgAl 0.9 La 0.1- Transfer the LDO to the constant temperature zone of a reaction tube, then load the ethanol dehydrogenation catalyst Cu / ZnO, and fill the remaining part of the reaction tube with quartz sand of 20 - 40 mesh. Install the reaction tube onto a micro fixed-bed reaction device and leak-check it with N2; Step 2: Pretreat the catalyst at 300 - 400 °C for 1 h on the micro fixed-bed device under a hydrogen atmosphere; after pretreatment, control the temperature at 300 °C and introduce a mixture of N2 and ethanol vapor. The flow rate of N2 is set at 40 mL / min, and chromatographically pure ethanol is pumped into a 200 °C vaporization chamber at a flow rate of 0.4 mL / h using a liquid injection pump for vaporization to generate C 4+ oxygenates.

[0069] The products are analyzed using an on-line chromatograph. Since ethanol first reacts with the aldol condensation catalyst, there are too many by-products from the dehydration reaction. The ethanol conversion rate is 84%, and the selectivity for C 4+ oxygenates is 26%.

[0070] Comparative Example 2 The type and loading method of the catalyst used are different from those in Example 1. A one-stage traditional catalyst system Cu 0.4 / Zn 0.02 Mg3Al 0.9 La 0.1 -LDO is used.

[0071] The steps are as follows: Step 1: Press the catalyst Cu 0.4 / Zn 0.02 Mg3Al 0.9 La 0.1 -LDO into tablets of a certain thickness using a tablet press, then granulate and screen to obtain particles of 20 - 40 mesh, load them into the constant temperature zone of a reaction tube, and fill the remaining part of the reaction tube with quartz sand of 20 - 40 mesh. Install the reaction tube onto a micro fixed-bed reaction device and leak-check it with N2; Step 2: Pretreat the catalyst at 300 - 400 °C for 1 h on the micro fixed-bed device under a hydrogen atmosphere; after pretreatment, control the temperature at 300 °C and introduce a mixture of N2 and ethanol vapor. The flow rate of N2 is set at 40 mL / min, and chromatographically pure ethanol is pumped into a 200 °C vaporization chamber at a flow rate of 0.4 mL / h using a liquid injection pump for vaporization to generate C 4+ oxygenates; Among them, the preparation process of Cu 0.4 / Zn 0.02 Mg3Al 0.9 La 0.1 -LDO is as follows: Dissolve Mg(NO3)2, Al(NO3)3, La(NO3)3, Cu(NO3)2, and Zn(NO3)2 salts in an aqueous solution with a metal ion molar concentration of 0.3 mol / L; add sodium hydroxide and anhydrous sodium carbonate to water to prepare an alkali solution with a concentration of 0.75 mol / L, where the molar ratio of sodium hydroxide to anhydrous sodium carbonate is 4:1; The molar ratio of each metal salt solution to the alkali solution is 4:1; Mix the salt solution and the alkali solution under sufficient stirring and then perform static crystallization at 65 °C for 10 - 18 h; Wash the obtained solid 2 - 5 times, place it in an oven and dry it for 12 h to obtain a catalyst precursor; Then place the catalyst precursor in a porcelain boat and calcine it at 600 °C for 0.5 - 6 h to obtain the metal composite oxide Cu 0.4 / Zn 0.02 Mg3Al 0.9 La 0.1 -LDO; Take a certain amount of Cu 0.4 / Zn 0.02 Mg3Al 0.9 La 0.1 -LDO in a porcelain boat and reduce it in a hydrogen atmosphere at 350 °C for 1 h to obtain Cu 0.4 / Zn 0.02 Mg3Al 0.9 La 0.1 -LDO.

[0072] Table 1 Catalytic performance tests of Examples 1 - 3 and Comparative Examples 1 and 2 under different catalyst loading methods

[0073] As can be seen from the results in Table 1, when using a dual - bed layer to load the ethanol dehydrogenation catalyst and the aldol condensation catalyst for the step - by - step relay preparation of C 4+ the conversion rate and selectivity of oxygenated compounds are the highest, reaching up to 80% and 82% respectively; when the order of the dual - bed layer loaded catalysts in Comparative Example 1 is opposite to that in Example 1, the reactants first react with the aldol condensation catalyst and then with the ethanol dehydrogenation catalyst, resulting in an increase in the by - products of the dehydration reaction of ethanol, so the selectivity decreases significantly; when using a one - stage traditional catalytic system in Comparative Example 2, it also causes an increase in the by - products of the dehydration reaction of ethanol, leading to a significant reduction in selectivity.

[0074] Example 4 As Figure 3 shown in (1), use a dual - bed layer to sequentially load the ethanol dehydrogenation catalyst and the aldol condensation catalyst to test the catalytic performance of different mass ratios of the ethanol dehydrogenation catalyst and the aldol condensation catalyst loaded in the dual - bed layer for the preparation of C 4+Activity influence of oxygen-containing compounds.

[0075] Step 1: The ethanol dehydrogenation catalyst Cu / ZnO and the aldol condensation catalyst MgAl 0.9 La 0.1 -LDO were each pressed into tablets of a certain thickness using a tablet press, granulated, and sieved to obtain particles with a mesh size of 20-40. Then, they were filled into the isothermal regions of 4 reaction tubes in sequence according to the mass ratios of 1:1, 1:5, 1:9, and 1:12. The remaining parts of the reaction tubes were filled with quartz sand of 20-40 mesh. The reaction tubes were installed on a micro fixed-bed reaction device and leak-tested with N2. Step 2: The catalyst was pretreated at 300-400 °C for 1 h on the micro fixed-bed device under a hydrogen atmosphere. After pretreatment, the temperature was controlled at 300 °C, and N2 and ethanol vapor were mixed and introduced. The flow rate of N2 was set at 40 mL / min, and chromatographically pure ethanol was pumped into a 200 °C vaporization chamber at a flow rate of 0.4 mL / h using a liquid injection pump for vaporization to generate C 4+ Oxygen-containing compounds.

[0076] The products were analyzed using an on-line chromatograph. The results are shown in Table 2. When the ethanol dehydrogenation catalyst and the aldol condensation catalyst were used with different mass ratios in the packed bed layers, the performance influence of ethanol catalytic preparation of C 4+ Oxygen-containing compounds.

[0077] Table 2 Performance influence of different mass ratios in the packed bed layers on ethanol catalytic preparation of C 4+ Oxygen-containing compounds

[0078] As shown in the results of Table 2, on the premise of ensuring the highest ethanol dehydrogenation conversion, as the mass of the aldol condensation catalyst increases, the contact time between acetaldehyde and the aldol condensation catalyst increases, resulting in an increase in the ability of acetaldehyde conversion. When the loading ratio of the ethanol dehydrogenation catalyst to the aldol condensation catalyst is 1:9, the acetaldehyde conversion ability reaches the highest and remains balanced.

[0079] Example 5 As Figure 3 shown in (1), a double-bed layer was used to sequentially pack the ethanol dehydrogenation catalyst and the aldol condensation catalyst, and the activity influence of the double-bed layer packed with the ethanol dehydrogenation catalyst and the aldol condensation catalyst with different La contents on ethanol catalytic preparation of C 4+ Oxygen-containing compounds.

[0080] Step 1: The ethanol dehydrogenation catalyst Cu / ZnO obtained in the preparation example and the aldol condensation catalysts MgAl-LDO (control group) with different La contents and MgAl 0.95 La 0.05-LDO, MgAl 0.9 La 0.1 -LDO, MgAl 0.85 La 0.15 -LDO was each pressed into tablets of a certain thickness using a tablet press, granulated, and sieved to obtain particles with a mesh size of 20 - 40. Then, according to the mass ratio of 1:9 of the ethanol dehydrogenation catalyst to the aldol condensation catalyst, they were successively loaded into the isothermal zone of 4 reaction tubes, and the remaining parts of the reaction tubes were filled with 20 - 40 mesh quartz sand. The reaction tubes were installed on a micro fixed-bed reaction device and leak-tested with N2; Step 2: The catalyst was pretreated on the micro fixed-bed device at 300 - 400 °C for 1 h, and the treatment atmosphere was hydrogen; after pretreatment, the temperature was controlled at 300 °C, and N2 and ethanol vapor were mixed and introduced. The flow rate of N2 was set at 40 mL / min, and chromatographically pure ethanol was pumped into a 200 °C vaporization chamber at a flow rate of 0.4 mL / h using a liquid injection pump for vaporization to generate C 4+ oxygenates.

[0081] The products were analyzed using an on-line chromatograph, and the results are shown in Table 3.

[0082] Table 3 Influence of Condensation Catalysts with Different La Contents on the Performance of Catalytic Preparation of C 4+ Oxygenates from Ethanol

[0083] As shown in the results of Table 3, the aldol condensation of acetaldehyde utilized the synergistic effect of the acid-base active sites of the aldol condensation catalyst. The increase in the La content regulated the acidity and basicity of the aldol condensation catalyst. When the La content was 0.1 (La / Al ratio was 1:9), the acid-base ratio of La gave the best aldol condensation of acetaldehyde.

[0084] Example 6 As Figure 3 shown in (1), a double-bed layer was used to successively load the ethanol dehydrogenation catalyst and the aldol condensation catalyst, and the influence of different ethanol flow rates on the activity of catalytic preparation of C4+ oxygenates from ethanol was tested.

[0085] Step 1: The ethanol dehydrogenation catalyst Cu / ZnO and the aldol condensation catalyst MgAl 0.9 La 0.1 -LDO obtained in the preparation example were each pressed into tablets of a certain thickness using a tablet press, granulated, and sieved to obtain particles with a mesh size of 20 - 40. Then, according to the mass ratio of 1:9, they were successively loaded into the isothermal zone of a reaction tube, and the remaining part of the reaction tube was filled with 20 - 40 mesh quartz sand. The reaction tube was installed on a micro fixed-bed reaction device and leak-tested with N2; Step 2: Pretreat the catalyst on a micro fixed-bed device at 300 - 400 °C for 1 h under a hydrogen atmosphere; after pretreatment, control the temperature at 300 °C and mix and introduce N2 and ethanol vapor. The flow rate of N2 is set at 40 mL / min, and chromatographically pure ethanol is pumped into a 200 °C vaporization chamber at different flow rates using a liquid injection pump for vaporization to generate C 4+ oxygenates.

[0086] Analyze the products using on-line chromatography, and the results are shown in Table 4.

[0087] Table 4 Influence of different ethanol flow rates on the performance of catalytic preparation of C 4+ oxygenates

[0088] As shown in the results of Table 4, as the ethanol injection flow rate increases, the amount and rate of acetaldehyde production also increase, and the rate of acetaldehyde condensation also increases to produce C4+ oxygenates. When the ethanol flow rate reaches 0.6 mL / h, the acetaldehyde conversion ability reaches equilibrium.

[0089] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A catalyst for the preparation of C4+ oxygenates by ethanol hierarchical relay, characterized in that, The catalyst includes an ethanol dehydrogenation catalyst and an aldol condensation catalyst. The active metal of the ethanol dehydrogenation catalyst is selected from at least one of Cu, Ni, Co, Ag, Pd, Rh, Ru, Pt, Ir, and Zn, and the carrier of the ethanol dehydrogenation catalyst is a metal oxide, selected from at least one of SiO2, ZnO, MnOx (the range of x is 1-14), and TiO2; wherein, the molar ratio of the metal oxide to the active metal is (0.1~5.0):

1. The aldol condensation catalyst is MgAlX-LDO, and X is selected from at least one of Cu, Zn, Ni, Ru, Ag, Co, La, and Zr; wherein, the molar ratio of Mg to Al+X is (1~5):1, and the molar ratio of X to Al is (0.01~1.0):

1. Among them, the mass ratio of the ethanol dehydrogenation catalyst to the aldol condensation catalyst is 1:(5~20).

2. The catalyst according to claim 1, wherein The ethanol dehydrogenation catalyst is 20-40 mesh particles obtained by tabletting, granulating, and sieving; the aldol condensation catalyst is 20-40 mesh particles obtained by tabletting, granulating, and sieving.

3. The catalyst according to claim 1, characterized in that, In the aldol condensation catalyst, the molar ratio of X to Al is 0.15:0.85, 0.1:0.9, or 0.05:0.

95.

4. The catalyst according to claim 1, wherein The preparation method of the ethanol dehydrogenation catalyst is as follows: Step T1: Prepare the active metal organic framework product Add the metal oxide to DMF and stir ultrasonically to obtain a suspension, denoted as solution A. The molar ratio of the metal oxide to DMF is (0.01-1):1; prepare a salt solution of the active component, denoted as solution B, with a concentration of 0.2~0.8 mol / L; prepare an alcohol solution of trimesic acid, denoted as solution C, with a concentration of 0.1~1.0 mol / L. Mix solution A, solution B, and solution C at 30~80°C, stir, and then let stand for 1~10 h. Centrifuge to obtain a solid, wash the obtained solid, and place it in an oven at 60-80°C for drying for 1~24 h to obtain the active metal organic framework product. In step T2: Calcination reaction Place the active metal organic framework obtained in step T1 in a porcelain boat and calcine it at 200~700°C for 0.5~6 h to obtain a catalyst precursor. In step T3: Hydrogen reduction Place the catalyst precursor obtained in step T2 in a porcelain boat and reduce it in a hydrogen atmosphere at 100~500°C for 0.1~4 h to obtain the ethanol dehydrogenation catalyst.

5. The catalyst according to claim 1, characterized in that, The preparation method of the aldol condensation catalyst is as follows: Step S1: Precipitation and crystallization Prepare corresponding metal salt solutions of metal Mg, metal Al, and metal X respectively, and control the concentration of each metal salt solution to 0.1~1.0 mol / L; add sodium hydroxide and anhydrous sodium carbonate to water to prepare an alkali solution with a concentration of 0.1-10 mM. Mix each metal salt solution and the alkali solution under sufficient stirring and let stand at 30~100°C for 1~24 h. Wash the obtained solid 2~5 times and bake it for 1~24 h to obtain a catalyst precursor. Step S2: Calcination reaction Place the catalyst precursor obtained in step S1 in a porcelain boat and calcine it at 400-700 °C for 0.5-6 h to obtain MgAlX-LDO, which is the aldol condensation catalyst.

6. A method for preparing oxygen-containing compounds by ethanol fractional relay, characterized in that, 4+ The method includes the following steps: Step 1: Load the ethanol dehydrogenation catalyst and the aldol condensation catalyst according to any one of claims 1-5 into a reaction tube, and install the reaction tube into a fixed-bed reactor; Step 2: Heat-treat the loaded catalyst at 300-400 °C for 0.5-3 h under a hydrogen or inert gas atmosphere; then vaporize ethanol and mix it with other inert gases and feed them into the above fixed-bed reactor, and carry out a catalytic reaction at 120 °C - 480 °C and a pressure of 1-100 atm to produce C 4+ oxygenates.

7. The method according to claim 6, characterized in that, In step 2, the ethanol is pumped into a vaporization chamber at 200 °C at a flow rate of 0.4-20.0 mL / h for vaporization.

8. The method according to claim 6, characterized in that In step 2, the flow rate of the inert gas is set to 20-200 mL / min.

9. The method according to claim 6, wherein In step 2, the inert atmosphere includes at least one of Ar, N2, and He.

10. The method according to claim 6, wherein In Step 2, the ethanol conversion rate is 70-85%, and the selectivity of oxygenates is 82-95%. 4+ ​

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