Oxide-loaded bimetallic heterogeneous catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, and provides an oxide-loaded bimetallic heterogeneous catalyst as well as a preparation method and application thereof. The preparation method of the oxide-loaded bimetallic heterogeneous catalyst comprises the following steps: covalently loading a first active metal and a second active metal on an oxide carrier under the assistance of urea hydrolysis, and calcining to obtain the oxide-loaded bimetallic heterogeneous catalyst, the ratio of the molar weight of the urea to the sum of the molar weights of the first active metal and the second active metal in terms of elementary substances is less than 50; the first active metal is selected from at least one of Rh, Pb, Ir and Ru; and the second active metal is selected from at least one of Cu, Zn, Ni, Co and Mn. The preparation method provided by the invention is simple, and expensive phosphorus-containing organic ligands do not need to be used; compared with the existing bimetallic heterogeneous catalyst, the prepared catalyst has the advantages that the catalytic performance of the active metal is better, and the stability is very good.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and more particularly to an oxide-supported bimetallic heterogeneous catalyst and a preparation method and application thereof. Background Art

[0002] Hydroformylation is the carbonylation process in which olefins react with synthesis gas (CO / H2) to produce aldehydes. The aldehyde groups generated by hydroformylation can be further converted into imines, amines, hemiacetals, acetals, aminals, carboxyl groups, hydroxyl groups, and other groups. Aldehydes produced by hydroformylation are widely used in the synthesis of fine chemicals such as plasticizers, surfactants, pharmaceuticals, pesticides, and flavorings. The growing demand for aldehydes and alcohols in the chemical industry, coupled with the abundant supply of inexpensive olefins from the petroleum industry, has driven the rapid development of hydroformylation.

[0003] Currently, my country's hydroformylation reactions still use homogeneous catalysts based primarily on rhodium-phosphine complexes. Although these catalysts have high activity and selectivity, subsequent separation and processing are difficult and costly, especially for long-chain olefin reactions. Furthermore, the high price and water sensitivity of the phosphine-containing ligands themselves also hinder the industrial development of hydroformylation reactions. Compared with homogeneous hydroformylation catalysts, heterogeneous hydroformylation catalysts have the advantage of being easily separated from the reaction solvent or olefin reactants (especially olefins with a carbon number greater than 6). Industrially, heterogeneous hydroformylation catalysts are often prepared by supporting precious metals (such as Pt, Pd, and Rh) on oxide surfaces. However, the surface energy of most active metals is greater than that of the solid support, which makes the active metals easily aggregate when highly loaded on the oxide support surface, which greatly affects the performance of the resulting heterogeneous catalyst. Therefore, ensuring efficient loading of the active metals on the oxide support while achieving high dispersion remains a major goal in the design of heterogeneous catalytic hydroformylation catalysts and a research hotspot in this field.

[0004] Wang et al. (Ind.Eng.Chem.Res.2020,42:18771-18780) simultaneously prepared bimetallic catalysts Rh-Co / SiO2 and monometallic catalysts Rh / SiO2, and confirmed that the addition of the second active metal Co is beneficial to the dispersion of the first active metal Rh, thereby achieving the purpose of improving catalytic activity. In order to further improve the effect of catalytic hydroformylation reaction, the team (ACS Catalysis,2021,11:9850-9859) modified the two active metals Co and Rh loaded on the surface of SiO2 with triphenylphosphine, so as to achieve high load and high dispersion by means of the coordination bond formed between the P atom in the organic phosphine ligand and the active metal, thereby improving the performance of the catalyst. However, the catalyst has failed to get rid of the limitations of phosphine-containing ligands, the preparation process is complicated, and an oxygen-free environment is required, and the cost is relatively high.

[0005] Therefore, it is very meaningful to provide a method for preparing a heterogeneous catalyst that improves the dispersion of the two-component metal on the oxide support without using a phosphine ligand. Summary of the Invention

[0006] The purpose of the present invention is to provide an oxide-supported bimetallic heterogeneous catalyst and its preparation method and application, so as to solve the technical problems in the prior art such as poor catalytic performance due to low loading and easy agglomeration, high cost due to the use of phosphine-containing ligands, and environmentally unfriendly phosphorus waste.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a method for preparing an oxide-supported bimetallic heterogeneous catalyst, comprising: covalently loading a first active metal and a second active metal on an oxide support with the aid of urea hydrolysis, and then calcining to obtain the oxide-supported bimetallic heterogeneous catalyst;

[0009] The ratio of the molar amount of the urea to the sum of the molar amounts of the first active metal and the second active metal as elements is less than 50;

[0010] The first active metal is selected from at least one of Rh, Pb, Ir, and Ru;

[0011] The second active metal is selected from at least one of Cu, Zn, Ni, Co, and Mn.

[0012] According to some embodiments of the present invention, the content of the first active metal in the catalyst as a single substance is 0.01 to 5 wt%, for example, 0.01 wt%, 0.02 wt%, 0.04 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%, 0.65 wt%, 0.7 wt%. %, 0.75wt%, 0.78wt%, 0.8wt%, 0.82wt%, 0.84wt%, 0.88wt%, 0.9wt%, 1wt%, 1.05wt%, 1.1wt%, 1.2w t%, 1.3wt%, 1.4wt%, 1.5wt%, 1.7wt%, 2wt%, 2.5wt%, 3wt%, 3.3wt%, 3.8wt%, 4wt%, 4.5wt%, 5wt%, etc.

[0013] According to some embodiments of the present invention, the content of the first active metal in the catalyst is 0.1 to 3 wt % based on the elemental content.

[0014] According to some embodiments of the present invention, the content of the first active metal in the catalyst is 0.5-1.5 wt % based on the elemental content.

[0015] According to some embodiments of the present invention, the content of the second active metal in the catalyst on a simple basis is 0.002-6 wt%, for example, 0.002 wt%, 0.004 wt%, 0.005 wt%, 0.008 wt%, 0.01 wt%, 0.02 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt%, 0.1 wt%, 0.12 wt%, 0.15 wt%, 0.18 wt%, 0.2 wt%, 0.25 wt%, 0.3wt%, 0.4wt%, 0.42wt%, 0.43wt%, 0.45wt%, 0.48wt%, 0.5wt%, 0.52wt%, 0.54wt%, 0.57wt%, 0.6wt%, 0 .7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.2wt%, 1.5wt%, 1.9wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 5wt%, 6wt%, etc.

[0016] According to some embodiments of the present invention, the content of the second active metal in the catalyst is 0.05 to 2 wt % based on the elemental content.

[0017] According to some embodiments of the present invention, the content of the second active metal in the catalyst is 0.2-0.6 wt % based on the elemental content.

[0018] According to some embodiments of the present invention, the ratio of the molar amount of the urea to the sum of the molar amounts of the first active metal and the second active metal calculated as elements is less than 45.

[0019] According to some embodiments of the present invention, the ratio of the molar amount of urea to the sum of the molar amounts of the first active metal and the second active metal calculated as elements is less than 42.

[0020] According to some embodiments of the present invention, the ratio of the molar amount of the urea to the sum of the molar amounts of the first active metal and the second active metal calculated as elements is ≤40.

[0021] According to some embodiments of the present invention, the ratio of the molar amount of the urea to the sum of the molar amounts of the first active metal and the second active metal in terms of elemental amounts is 10-40.

[0022] According to some embodiments of the present invention, the ratio of the molar amount of the urea to the sum of the molar amounts of the first active metal and the second active metal in terms of elemental amounts is 20-40.

[0023] According to some embodiments of the present invention, the first active metal is Rh.

[0024] In the present invention, if Rh is selected as the first active metal, the prepared catalyst is suitable for the hydroformylation of various olefins, including olefins that are relatively difficult to react, such as isooctene. If other first active metals are used, the prepared catalyst is generally more suitable for the hydroformylation of α-olefins, but has relatively poor catalytic performance for olefins that are relatively difficult to react, such as isooctene.

[0025] According to some embodiments of the present invention, the second active metal includes Co and / or Zn.

[0026] In the present invention, the second active metal is selected from at least one of Co and Zn, which can make the catalyst have better catalytic performance compared with using other types of second active metals.

[0027] According to some embodiments of the present invention, the second active metal is Co.

[0028] According to some embodiments of the present invention, the particle size of the oxide carrier is ≤100 μm, and the specific surface area is ≥200 m 2 / g.

[0029] According to some embodiments of the present invention, the particle size of the oxide carrier is 30 to 100 μm, and the specific surface area is 200 to 250 m 2 / g.

[0030] According to some embodiments of the present invention, the oxide support is modified by C doping.

[0031] According to some embodiments of the present invention, the C doping modification includes: dispersing the oxide support and the carbon source in water, stirring and mixing, evaporating the water, crushing the obtained solid, and then performing a gas-phase hydrothermal reaction to obtain the C-doped modified oxide support.

[0032] According to some embodiments of the present invention, the stirring and mixing is carried out for 20 to 60 minutes to ensure that the oxide support and the carbon source are evenly mixed.

[0033] In the present invention, various common methods can be used to evaporate the water, such as heating.

[0034] In the present invention, the purpose of pulverizing the obtained solid is to disperse the solid agglomerated during the volatilization of water, so as to make the particles of the C-doped modified oxide support more uniform. Various common solid dispersion operations such as grinding can be used.

[0035] According to some embodiments of the present invention, the conditions of the gas-phase hydrothermal reaction include: reaction temperature of 160-220° C., preferably 180-200° C., and reaction time of 2-20 h, preferably 6-15 h.

[0036] According to some embodiments of the present invention, the C doping modification further comprises: washing and drying the product after the gas phase hydrothermal reaction.

[0037] According to some embodiments of the present invention, the carbon source includes at least one of glucose, mannose, maltose, chitosan, sodium alginate, and cellulose.

[0038] In the present invention, glucose is used as a carbon source to prepare the oxide support for C doping modification. Compared with other types of carbon sources, the catalytic performance of the finally prepared catalyst is better and it is also more advantageous from a cost perspective.

[0039] According to some embodiments of the present invention, the mass ratio of the carbon source to the oxide support is 0.1 to 0.5, for example, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0040] Preferably, the mass ratio of the carbon source to the oxide carrier is 0.2 to 0.4.

[0041] According to some embodiments of the present invention, the oxide support includes at least one of a metal oxide, a non-metal oxide, a zeolite containing a metal oxide and / or a non-metal oxide, or a molecular sieve.

[0042] According to some embodiments of the present invention, the oxide support comprises Al2O3.

[0043] According to some embodiments of the present invention, the oxide support comprises γ-Al2O3.

[0044] According to some embodiments of the present invention, the preparation method comprises the following steps:

[0045] S1. The oxide support is added to the solvent and stirred to obtain a first dispersion;

[0046] S2. The first active metal precursor and the second active metal precursor are added to the first dispersion, stirred and mixed to obtain a second dispersion;

[0047] S3. Urea is added to the second dispersion and mixed, and the temperature is raised to 50 to 100 ° C and stirred for reaction;

[0048] S4. After the reaction is completed, the reaction solution is cooled to room temperature and then solid-liquid separation is performed, and the obtained solid is calcined to obtain the oxide-supported bimetallic heterogeneous catalyst.

[0049] In the preparation method of the oxide-supported bimetallic heterogeneous catalyst provided by the present invention, the first active metal and the second active metal are combined with the oxide support (YO) in the dispersion through weak electrostatic interaction; after urea is added to the dispersion, the urea is hydrolyzed to produce NH3 and NH4 + , CO2 and HCO3 - NH3 preferentially complexes with the first active metal and the second active metal to form and At the same time, as urea hydrolyzes, the pH of the dispersion increases (from acidic to weakly acidic), causing the hydroxyl groups on the surface of the oxide support to lose protons and convert into oxygen anions YO - . Then, YO - and and The combination of YO-M1 covalent bond and YO-M2 covalent bond replaces the weak electrostatic interaction between the active metal and the oxide carrier, effectively overcoming the agglomeration force between the metals, thereby ensuring high dispersion at high loads. and The residual positive charge can prevent or reduce weak electrostatic bonding and Aggregation at the same site facilitates further dispersion of the first active metal and the second active metal on the oxide support.

[0050] In the present invention, by first allowing the first active metal and the second active metal to bind to the oxide support through weak electrostatic interaction and then adding urea, while ensuring efficient loading of the active metals, it is also possible to prevent the reaction of some active metals with weak acid anions (such as HCO3) during the process of increasing the pH of the dispersion due to urea hydrolysis. - OH - etc.) first form a precipitate.

[0051] In the present invention, by controlling the amount of urea added so that the molar ratio of urea to the first active metal and the second active metal (calculated as simple substances) is less than 50, the pH of the dispersion at the time of reaction termination can be controlled within the range of 5 to 7, and neither the first active metal nor the second active metal will form a precipitate with the weak acid ions in the dispersion.

[0052] According to some embodiments of the present invention, the first active metal precursor includes at least one of a chloride salt and a nitrate salt of the first active metal.

[0053] According to some embodiments of the present invention, the first active metal precursor includes at least one of a chloride salt and a nitrate salt of Rh.

[0054] According to some embodiments of the present invention, the first active metal precursor includes at least one of RhCl3, RhCl3·xH2O (such as RhCl3·3H2O), Rh(NO3)3, and Rh(NO3)3·2H2O.

[0055] According to some embodiments of the present invention, the second active metal precursor includes at least one of a nitrate, a sulfate, and a chloride of the second active metal.

[0056] According to some embodiments of the present invention, the second active metal precursor includes at least one of nitrate, sulfate, and chloride of Co.

[0057] According to some embodiments of the present invention, the second active metal precursor includes at least one of Co(NO3)2, Co(NO3)2·6H2O, CoSO4, CoSO4·7H2O, CoCl2, and CoCl2·6H2O.

[0058] According to some embodiments of the present invention, the concentration of the oxide carrier in the first dispersion is 0.5 to 10 wt%, for example, it can be 0.5 wt%, 0.6 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, etc.

[0059] Preferably, the concentration of the oxide carrier in the first dispersion is 0.8-5 wt %.

[0060] More preferably, the concentration of the oxide carrier in the first dispersion is 1 to 3 wt %.

[0061] According to some embodiments of the present invention, the molar concentration of the first active metal precursor in the second dispersion is 0.1 to 10 mmol / L, for example, it can be 0.1 mmol / L, 0.2 mmol / L, 0.3 mmol / L, 0.4 mmol / L, 0.5 mmol / L, 0.6 mmol / L, 0.7 mmol / L, 0.8 mmol / L, 0.9 mmol / L, 1.0 mmol / L, 1.1 mmol / L, 1.2 mmol / L, 1.3 mmol / L, 1.4 mmol / L, 1.5 mmol / L, 1.8 mmol / L, 2 mmol / L, 2.5 mmol / L, 3 mmol / L, 4 mmol / L, 5 mmol / L, 6 mmol / L, 7 mmol / L, 8 mmol / L, 9 mmol / L, 10 mmol / L, etc.

[0062] Preferably, the molar concentration of the first active metal precursor in the second dispersion is 0.3 to 3 mmol / L.

[0063] More preferably, the molar concentration of the first active metal precursor in the second dispersion is 0.5 to 1.5 mmol / L.

[0064] According to some embodiments of the present invention, the molar ratio of the first active metal precursor calculated as a metal element to the second active metal precursor calculated as a metal element is 1:(0.1-2), for example, it can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, etc.

[0065] According to some embodiments of the present invention, the molar ratio of the first active metal precursor calculated as a single metal to the second active metal precursor calculated as a single metal is 1:(0.5-1.5).

[0066] According to some embodiments of the present invention, the stirring and mixing in step S1 is performed at room temperature for 5 to 15 minutes.

[0067] According to some embodiments of the present invention, the stirring and mixing in step S2 is carried out at a temperature of 25 to 60° C. and for a time of 8 to 12 hours.

[0068] According to some embodiments of the present invention, the temperature of the stirring reaction in step S3 is 80-90°C.

[0069] According to some embodiments of the present invention, the stirring reaction time in step S3 is 2 to 6 hours, preferably 4 to 6 hours.

[0070] According to some embodiments of the present invention, in step S4, drying is performed before calcination; preferably, the drying is vacuum drying.

[0071] According to some embodiments of the present invention, the calcination in step S4 is performed in an inert atmosphere.

[0072] According to some embodiments of the present invention, the inert atmosphere includes at least one of nitrogen and an inert gas.

[0073] According to some embodiments of the present invention, the calcination in step S4 includes performing step-by-step continuous calcination in multiple temperature intervals within the range of room temperature to 600°C.

[0074] According to some embodiments of the present invention, the calcination includes: first heating the temperature to 200°C at a heating rate of 1-10°C / min and holding the temperature for 1-2 hours; then heating the temperature to 300-600°C at a heating rate of 1-2°C / min and holding the temperature for 3-10 hours.

[0075] According to some embodiments of the present invention, after the calcination in step S4 is completed, the material is cooled to room temperature at a rate of 1 to 10° C. / min or a natural cooling rate.

[0076] According to some embodiments of the invention, the solvent comprises water.

[0077] In a second aspect, the present invention provides an oxide-supported bimetallic heterogeneous catalyst prepared by the preparation method described in the first aspect.

[0078] According to some embodiments of the present invention, the content of the first active metal component in the catalyst, calculated as an element, is (0.01 to 5.0) wt%, preferably (0.1 to 3.0) wt%, and more preferably (0.5 to 1.5) wt%;

[0079] The content of the second active metal component in the catalyst calculated as an element is (0.002-6.0) wt%, preferably (0.05-2.0) wt%, and more preferably (0.2-0.6) wt%.

[0080] In a third aspect, the present invention provides use of the oxide-supported bimetallic heterogeneous catalyst described in the second aspect in a heterogeneous catalytic reaction, especially an olefin hydroformylation reaction.

[0081] The beneficial effects of the present invention are at least:

[0082] The preparation method of the oxide-supported bimetallic heterogeneous catalyst provided by the present invention is simple and does not require the use of expensive phosphorus-containing organic ligands. Compared with existing bimetallic heterogeneous catalysts, the prepared oxide-supported bimetallic heterogeneous catalyst has higher dispersibility and loading of active metal components, better catalytic performance, excellent catalytic performance for olefin hydroformylation, especially high-carbon olefin hydroformylation reaction, and good stability, and has broad industrial application prospects in the field of heterogeneous catalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 This is a morphology of the active metal on the catalyst prepared in Example 1.

[0084] Figure 2 This is a morphology of the active metal on the catalyst prepared in Comparative Example 1.

[0085] The morphology of the active metal on the catalyst was measured using a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM, instrument model Talos F200S G2 energy spectrum SUPER X). DETAILED DESCRIPTION

[0086] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate this patent in detail and do not limit the scope of protection of the present invention in any way.

[0087] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following examples, etc., are all commercially available or can be obtained by existing methods; the reagent amounts used, unless otherwise specified, are the amounts used in conventional experimental procedures; and the experimental methods described, unless otherwise specified, are all conventional methods.

[0088] In the various embodiments and comparative examples of the present invention, the particle size of the γ-Al2O3 used is 30 to 100 μm, and the specific surface area is 200 to 250 m 2 / g.

[0089] Example 1

[0090] 1 g of γ-Al2O3 was dispersed in 0.1 L of water and stirred at room temperature for 10 min. Then, 1 mL of a mixed aqueous solution of RhCl3 and Co(NO3)2 was added under stirring to make the molar concentration of RhCl3 in the dispersion 1 mmol / L and the molar concentration of Co(NO3)2 1 mmol / L. Subsequently, the mixture was stirred at a constant temperature of 25°C for 10 h. Urea was added to make the ratio of the molar amount of urea to the sum of the molar amounts of Rh (as a single substance) and Co (as a single substance) 40. After stirring and reacting at 80°C for 4 h, the above mixture was filtered and separated. The obtained solid was transferred to a vacuum drying oven and vacuum dried at 60°C for 8 h. After being taken out and weighed, a rhodium and cobalt bimetallic loaded product was obtained.

[0091] The above-mentioned bimetallic loaded product was transferred to a tube furnace. After nitrogen was introduced to completely replace the air in the tube furnace, the temperature was raised to 200°C at a rate of 10°C / min under a nitrogen atmosphere and then kept at this temperature for 1 hour. Then, the temperature was raised to 450°C at a rate of 1°C / min and kept at this temperature for 5 hours. After the constant temperature process, the heating was turned off and the product was naturally cooled to room temperature to obtain a Rh-Co / γ-Al2O3 bimetallic heterogeneous catalyst. The morphology of the active metal on the catalyst is shown in FIG. Figure 1 shown.

[0092] Example 2

[0093] The preparation method of the catalyst is similar to that of Example 1, except that the molar concentration of RhCl3 in the dispersion is 1 mmol / L and the molar concentration of Co(NO3)2 is 0.5 mmol / L.

[0094] Example 3

[0095] The preparation method of the catalyst is similar to that of Example 1, except that the molar concentration of RhCl3 in the dispersion is 1 mmol / L and the molar concentration of Co(NO3)2 is 1.5 mmol / L.

[0096] Example 4

[0097] The preparation method of the catalyst is similar to that of Example 1, except that the molar concentration of RhCl3 in the dispersion is 1 mmol / L and the molar concentration of Co(NO3)2 is 2 mmol / L.

[0098] Example 5

[0099] The preparation method of the catalyst is similar to that of Example 1, except that the ratio of the molar amount of urea to the sum of the molar amounts of Rh (as a single substance) and Co (as a single substance) is 10.

[0100] Example 6

[0101] The preparation method of the catalyst is similar to that of Example 1, except that the ratio of the molar amount of urea to the sum of the molar amounts of Rh (in elemental terms) and Co (in elemental terms) is 20.

[0102] Example 7

[0103] The preparation method of the catalyst is similar to that of Example 1, except that the ratio of the molar amount of urea to the sum of the molar amounts of Rh (in elemental terms) and Co (in elemental terms) is 30.

[0104] Example 8

[0105] The preparation method of the catalyst is similar to that of Example 1, except that the ratio of the molar amount of urea to the sum of the molar amounts of Rh (in elemental terms) and Co (in elemental terms) is 50.

[0106] Example 9

[0107] The preparation method of the catalyst is similar to that of Example 1, except that γ-Al2O3 is replaced by active Al2O3 (particle size of 30-100 μm, specific surface area of ​​167-192 m 2 / g).

[0108] Example 10

[0109] The catalyst preparation method is similar to that of Example 1, except that γ-Al2O3 is replaced by silicon dioxide (particle size of 30-100 μm, specific surface area of ​​200-250 m 2 / g).

[0110] Example 11

[0111] The catalyst preparation method is similar to that in Example 1, except that γ-Al2O3 is replaced by SBA-15 (particle size of 30-100 μm, specific surface area of ​​200-250 m 2 / g).

[0112] Example 12

[0113] The catalyst preparation method is similar to that in Example 1, except that γ-Al2O3 is replaced by ZSM-35 (particle size of 30-100 μm, specific surface area of ​​200-250 m 2 / g).

[0114] Example 13

[0115] The preparation method of the catalyst refers to Example 1, with the only difference being that the Co(NO3)2 in the mixed aqueous solution is replaced by an equimolar amount (based on the metal element) of ZnCl2.

[0116] Example 14

[0117] The preparation method of the catalyst is similar to that of Example 1, except that the Co(NO3)2 in the mixed aqueous solution is replaced by an equimolar amount (based on the metal element) of MnCl2·6H2O.

[0118] Example 15

[0119] The preparation method of the catalyst refers to Example 1, except that a mixed aqueous solution of RhCl3 and Co(NO3)2 is added to the dispersion, followed by constant temperature stirring at 25°C for 5 hours.

[0120] Example 16

[0121] The preparation method of the catalyst is similar to that of Example 1, except that the bimetallic loaded product is heated to 200°C at a rate of 10°C / min under a nitrogen atmosphere, and then the temperature is not kept constant for 1 hour. Instead, the temperature is immediately heated to 450°C at a rate of 1°C / min and then kept constant for 5 hours.

[0122] Example 17

[0123] The preparation method of the catalyst is similar to that of Example 1, except that the bimetallic loaded product is directly heated to 450°C at a rate of 10°C / min under a nitrogen atmosphere and then kept at this temperature for 5 hours.

[0124] Example 18

[0125] The preparation method of the catalyst is similar to that of Example 1, except that the RhCl3 in the mixed aqueous solution is replaced by an equimolar amount (based on the metal element) of IrCl3·6H2O.

[0126] Example 19

[0127] The preparation method of the catalyst is similar to that of Example 1, except that γ-Al2O3 is replaced by C-γ-Al2O3 of equal mass.

[0128] The preparation method of C-γ-Al2O3 includes: dispersing 1g of γ-Al2O3 in 20mL of deionized water, adding 0.3g of glucose, and magnetically stirring for 30 minutes. The resulting mixture is then placed in an oven and dried overnight at 60°C to completely evaporate the water. The resulting solid is lightly ground in a mortar and pestle, then transferred to a 10mL glass bottle. The glass bottle is placed in a 100mL polytetrafluoroethylene-lined reactor, and 5mL of deionized water is added between the glass bottle and the polytetrafluoroethylene liner. The reactor is placed in an oven at 180°C for 6 hours. After the reaction is completed, the reactor is naturally cooled to room temperature. The solid in the glass bottle is washed alternately with water and ethanol and then dried in a vacuum drying oven at 60°C for 8 hours to obtain C-γ-Al2O3.

[0129] Comparative Example 1

[0130] The preparation method of the catalyst is similar to that of Example 1, except that urea is not added during the preparation of the bimetallic supported product.

[0131] Specifically, the preparation method of the rhodium and cobalt bimetallic loaded product includes: dispersing 1g of γ-Al2O3 in 0.1L of water, stirring and mixing at room temperature for 10 minutes, adding 1mL of a mixed aqueous solution of RhCl3 and Co(NO3)2 under stirring, so that the molar concentration of RhCl3 in the dispersion is 1mmol / L and the molar concentration of Co(NO3)2 is 1mmol / L, then stirring at a constant temperature of 25°C for 10 hours, and then stirring and reacting at 80°C for 4 hours, filtering and separating the above mixture, transferring the obtained solid to a vacuum drying oven, vacuum drying at 60°C for 8 hours, taking out and weighing to obtain the rhodium and cobalt bimetallic loaded product.

[0132] The morphology of the active metal on the obtained catalyst is as follows Figure 2 shown.

[0133] Depend on Figure 1 and Figure 2 It can be seen that the catalyst preparation methods used in Example 1 and Comparative Example 1 can make the active metals evenly distributed on γ-Al2O3, but Figure 1 The average particle size of the active metal in Figure 2 This indicates that due to the auxiliary effect of urea, the active metal in the catalyst prepared in Example 1 is less likely to agglomerate than that in Comparative Example 1, and thus the dispersion is higher than that in Comparative Example 1.

[0134] Comparative Example 2

[0135] The preparation method of the catalyst refers to Example 1, with the only difference being that the aqueous solution contains only RhCl3 and does not contain Co(NO3)2; and the molar ratio of urea to Rh (as a single substance) is 40.

[0136] Comparative Example 3

[0137] The preparation method of the catalyst refers to Example 1, with the only difference being that a mixed aqueous solution of RhCl3 and Co(NO3)2 and urea are added to the dispersion at the same time, stirred at a constant temperature of 25°C for 10 hours, and then stirred at 80°C for 4 hours.

[0138] Comparative Example 4

[0139] The preparation method of the catalyst is similar to that of Example 18, except that urea is not added during the preparation of the bimetallic supported product.

[0140] Catalyst performance evaluation:

[0141] (1) Catalytic performance evaluation

[0142] Take 200 mg of each catalyst prepared in Example 1-17 or Comparative Example 1-3, mix them with 30 mL of isooctene and 10 mL of toluene, and transfer them into a high-pressure reactor. A CO / H2 mixed gas (the volume ratio of CO and H2 is 1:1) is introduced into the reactor. After replacing the air in the reactor, the pressure is increased to 6 MPa, stirring is started, and the reaction is carried out at a constant temperature of 100°C for 7 hours. The reaction results are shown in Table 1.

[0143] 200 mg of each catalyst prepared in Example 18 or Comparative Example 4 was taken, mixed with 3.5 mL of 1-octene and 10 mL of toluene, and then transferred to a high-pressure reactor. A CO / H2 mixed gas (the volume ratio of CO and H2 was 1:1) was introduced into the reactor. After replacing the air in the reactor, the pressure was increased to 10 MPa, stirring was started, and the reaction was carried out at a constant temperature of 150°C for 20 hours. The reaction results are shown in Table 1.

[0144] in:

[0145] (i) Conversion rate烯烃 =(n 烷烃 +n 醛 +n 醇 ) / (n 烷烃 +n 醛 +n 醇 +n 剩余的烯烃 )×100%.

[0146] (ii) Selectivity (醛+醇) =(n 醛 +n 醇 ) / (n 烷烃 +n 醛 +n 醇 )×100%.

[0147] n in the formula 烷烃 、n 醛 、n 醇 、n 剩余的烯烃 These refer to the molar amounts of alkane, aldehyde, alcohol, and unreacted olefin in the product, respectively.

[0148] (iii) First metal content and second metal content: measured using an inductively coupled plasma spectrometer (iCAP 6300).

[0149] Table 1

[0150]

[0151]

[0152] Note: The first metal content and the second metal content represent the content of the first active metal and the second active metal in the catalyst respectively based on the element.

[0153] (2) Stability evaluation

[0154] After the catalytic performance evaluation, the catalyst of Example 1 was separated from the reaction mixture, washed, and dried. The catalytic performance evaluation reaction in (1) was repeated. The results of the six-cycle reaction are shown in Table 2.

[0155] Table 2

[0156] Number of cycles Conversion rate (%) (aldehyde + alcohol) selectivity (%) 1 91.2 97.5 2 91.4 97.6 3 91.1 97.4 4 91.0 97.4 5 90.4 97.3 6 89.6 97.1

[0157] As can be seen from Table 2, after the catalyst provided by the present invention is recycled for 6 times, the conversion rate and selectivity only decrease by 1.8% and 0.4% respectively, and the catalyst has good stability.

[0158] From the above results, it can be seen that the oxide-supported bimetallic heterogeneous catalyst prepared in the present invention has excellent catalytic performance and stability in catalyzing the olefin hydroformylation reaction.

[0159] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing an oxide-supported bimetallic heterogeneous catalyst, characterized in that: include: The first active metal and the second active metal are covalently loaded on the oxide support with the aid of urea hydrolysis, and then calcined to obtain the oxide-supported bimetallic heterogeneous catalyst; The ratio of the molar amount of the urea to the sum of the molar amounts of the first active metal and the second active metal as elements is less than 50; The first active metal is selected from at least one of Rh, Pb, Ir, and Ru; The second active metal is selected from at least one of Cu, Zn, Ni, Co, and Mn.

2. The preparation method according to claim 1, characterized in that The content of the first active metal in the catalyst is 0.01 to 5 wt %, preferably 0.1 to 3 wt %, more preferably 0.5 to 1.5 wt % based on the elemental content; and / or the content of the second active metal in the catalyst, calculated as a single substance, is 0.002 to 6 wt%, preferably 0.05 to 2 wt%, more preferably 0.2 to 0.6 wt%; and / or the ratio of the molar amount of the urea to the sum of the molar amounts of the first active metal and the second active metal as elements is ≤40, preferably 10 to 40, more preferably 20 to 40; and / or, the first active metal is Rh; And / or, the second active metal comprises Co and / or Zn, preferably Co.

3. The preparation method according to claim 1 or 2, characterized in that The particle size of the oxide carrier is ≤100 μm and the specific surface area is ≥200 m 2 / g; Preferably, the particle size of the oxide carrier is 30 to 100 μm, and the specific surface area is 200 to 250 m 2 / g And / or, the oxide support comprises at least one of a metal oxide, a non-metal oxide, a zeolite or a molecular sieve containing a metal oxide and / or a non-metal oxide; preferably, the oxide support comprises Al2O3; more preferably, the oxide support comprises γ-Al2O3.

4. The preparation method according to any one of claims 1 to 3, characterized in that The oxide support is modified by C doping; Preferably, the C doping modification comprises: dispersing the oxide support and the carbon source in water, stirring and mixing, evaporating the water, pulverizing the obtained solid, and then performing a gas phase hydrothermal reaction to obtain the C doped and modified oxide support; More preferably, The carbon source includes at least one of glucose, mannose, maltose, chitosan, sodium alginate, and cellulose; And / or, the mass ratio of the carbon source to the oxide support is 0.1 to 0.5, preferably 0.2 to 0.

4.

5. The preparation method according to any one of claims 1 to 4, characterized in that The steps include: S1. The oxide support is added to the solvent and stirred to obtain a first dispersion; S2. The first active metal precursor and the second active metal precursor are added to the first dispersion, stirred and mixed to obtain a second dispersion; S3. Urea is added to the second dispersion and mixed, and the temperature is raised to 50 to 100 ° C and stirred for reaction; S4. After the reaction is completed, the reaction solution is cooled to room temperature and then solid-liquid separation is performed, and the obtained solid is calcined to obtain the oxide-supported bimetallic heterogeneous catalyst.

6. The preparation method according to claim 5, characterized in that The first active metal precursor includes at least one of a chloride salt and a nitrate salt of the first active metal; Preferably, the first active metal precursor includes at least one of a chloride salt and a nitrate salt of Rh; More preferably, the first active metal precursor includes RhCl3, RhCl 3· At least one of xH2O, Rh(NO3)3, and Rh(NO3)3·2H2O.

7. The preparation method according to claim 5 or 6, characterized in that: The second active metal precursor includes at least one of a nitrate, a sulfate, and a chloride of a second active metal; Preferably, the second active metal precursor comprises at least one of nitrate, sulfate and chloride of Co; Further preferably, the second active metal precursor includes at least one of Co(NO3)2, Co(NO3)2·6H2O, CoSO4, CoSO4·7H2O, CoCl2, and CoCl2·6H2O.

8. The preparation method according to any one of claims 5 to 7, characterized in that The concentration of the oxide carrier in the first dispersion is 0.5 to 10 wt %; and / or, the molar concentration of the first active metal precursor in the second dispersion is 0.1 to 10 mmol / L; And / or, the molar ratio of the first active metal precursor calculated as a single metal to the second active metal precursor calculated as a single metal is 1:(0.1-2), preferably 1:(0.5-1.5).

9. The preparation method according to any one of claims 5 to 8, characterized in that The stirring and mixing in step S2 is performed at a temperature of 25 to 60° C. and for a time of 8 to 12 hours; And / or, the stirring reaction temperature in step S3 is 80-90°C; And / or, the stirring reaction time in step S3 is 2 to 6 hours.

10. The preparation method according to any one of claims 5 to 9, characterized in that: The calcination in step S4 is carried out in an inert atmosphere; And / or, the calcination in step S4 includes performing step-by-step continuous calcination in multiple temperature intervals within the range of room temperature to 600° C.; preferably, the calcination includes: first heating to 200° C. at a heating rate of 1 to 10° C. / min, and holding the temperature for 1 to 2 hours; then heating to 300 to 600° C. at a heating rate of 1 to 2° C. / min, and holding the temperature for 3 to 10 hours; and / or, after the calcination in step S4 is completed, cooling to room temperature at a rate of 1 to 10° C. / min or a natural cooling rate; And / or, the solvent comprises water.

11. An oxide-supported bimetallic heterogeneous catalyst prepared by the preparation method according to any one of claims 1 to 10; Preferably, The content of the first active metal component in the catalyst is (0.01-5.0) wt%, preferably (0.1-3.0) wt%, and more preferably (0.5-1.5) wt%; The content of the second active metal component in the catalyst calculated as an element is (0.002-6.0) wt%, preferably (0.05-2.0) wt%, and more preferably (0.2-0.6) wt%.

12. Use of the oxide-supported bimetallic heterogeneous catalyst according to claim 11 in heterogeneous catalytic reactions, especially olefin hydroformylation reactions.

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