A high-loading rhenium monoatomic catalyst, a preparation method thereof and application thereof in aldehyde deuteration reaction

Abstract

The application belongs to the field of catalysis technology, and particularly relates to a high-loading-rate single-atom rhenium-based catalyst, a preparation method thereof and application of the catalyst in aldehyde deuteration reaction. A rhenium metal organic compound or a rhenium precursor is used as a rhenium source, a metal oxide is used as a carrier, the mass ratio of the rhenium source and the metal oxide is controlled to be 0.05-0.3:1, ball milling is carried out at room temperature for 0.5-20 hours, and catalyst precursor powder is collected after the ball milling is completed; the catalyst precursor powder is calcined at high temperature to obtain a metal oxide-loaded rhenium single-atom catalyst. The catalyst prepared by the application is a rhenium catalyst in an atomic dispersion state, and the mass loading rate of rhenium is relatively high. The catalyst has relatively high activity and deuteration selectivity, the deuteration rate of the catalyst is more than 150%, the catalytic route of the reaction process is realized, the catalyst does not change obviously after the reaction, the stability of the catalyst is good, and the catalyst has strong development potential.

Description

Technical Field

[0001] This invention belongs to the field of catalysis technology, specifically relating to a high-loading single-atom rhenium-based catalyst, its preparation method, and its application in aldehyde deuteration reactions. Background Technology

[0002] Single-atom catalysts are a class of catalysts in which metal atoms are independently dispersed on a support. These catalysts possess the highest atom utilization rate, significantly reducing the cost of traditional nanoparticle catalysts, especially supported noble metal catalysts, thus attracting considerable research interest. Compared to nanoparticle catalysts, single-atom catalysts offer advantages such as uniform active sites and maximized metal-support interface. Furthermore, single-atom catalysts combine the uniformity of active sites in homogeneous catalysts with the stability and ease of separation of heterogeneous catalysts, thus being considered a bridge between homogeneous and heterogeneous catalysis.

[0003] To prepare stable, high-performance single-atom catalysts, researchers have proposed a series of strategies, including defect engineering, confinement, and heteroatom coordination. After nearly a decade of development, researchers have successfully prepared single-atom catalysts of commonly used catalytic elements, and even some non-metallic elements have been reported. However, single-atom catalysts for rhenium, an important metal in homogeneous catalysis, have not yet been reported. Christopher's group has made numerous attempts to prepare rhenium single-atom catalysts. In 2019, they reported the preparation of a Rh-Re diatomic catalyst using an adsorption impregnation method. In 2020, they reported an atomically dispersed Re / SiO2 catalyst. During the Re preparation process, they added triethanolamine as a ligand to stabilize the rhenium metal and prevent agglomeration. However, in this catalyst, rhenium mainly exists in small clusters, and no truly meaningful rhenium single-atom catalyst has been reported. Summary of the Invention

[0004] This invention provides a rhenium-based catalyst with a high loading rate of single atoms, its preparation method, and its application in the deuteration reaction of aldehydes. The catalyst support is a metal oxide, and the active component is rhenium metal. The loading rate of the active component is 0.01–30 wt%, exhibiting high noble metal dispersion and high atom utilization. Its application in the deuteration reaction yielded high yields of deuterated products, realizing the catalytic route for this reaction process.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention provides a method for preparing a single-atom rhenium-based catalyst, the method comprising the following steps:

[0007] 1) Using rhenium organometallic compounds or rhenium precursors as the rhenium source and metal oxides as the support, the mass ratio of rhenium to metal oxides is controlled at 0.05-0.3:1. The mixture is ball-milled at room temperature for 0.5-20 hours. After ball milling, the catalyst precursor powder is collected.

[0008] 2) The catalyst precursor powder obtained in step 1) is calcined at high temperature to obtain a rhenium single-atom catalyst supported on a metal oxide.

[0009] Based on the above technical solution, preferably, the preparation method of the rhenium organometallic compound is as follows: under stirring conditions, a dinitrogen ligand is added to a tetrahydrofuran solvent, followed by the addition of a rhenium precursor, stirring is continued for 1-4 hours, the mixture is filtered, and vacuum dried at room temperature to obtain the rhenium organometallic compound.

[0010] Based on the above technical solution, preferably, the rhenium precursor includes one of ammonium perperurate, rhenium trioxide, rhenium heptaoxide, and methyl rhenium trioxide.

[0011] Based on the above technical solution, preferably, the dinitrogen ligand is one of o-phenanthroline, 5,12-dimethyl o-phenanthroline, 2,2-bispyridine, and 4,4-bispyridine.

[0012] Based on the above technical solution, preferably, the metal oxide in step 1) is one of titanium oxide, iron oxide, copper oxide, cerium oxide, silicon oxide, and aluminum oxide, preferably titanium oxide, with a size of 10-100 nm.

[0013] Based on the above technical solution, preferably, in step 2), the volume of the ball mill jar is one or more of 50mL, 100mL and 200mL, and the ball milling time is preferably 1-20h.

[0014] Based on the above technical solution, preferably, the calcination atmosphere in step 2) is one of air, nitrogen, argon, and hydrogen, the calcination temperature is 200-600℃, and the calcination time is 0.5-10h, preferably 0.5-8h.

[0015] In another aspect, the present invention provides a catalyst prepared by the above-described method, wherein metallic rhenium is dispersed in the form of single atoms on the surface of a metal oxide support, with a mass loading rate of 5-30%, preferably 5-20%.

[0016] In another aspect, the present invention provides the application of the above-mentioned catalyst in a deuteration reaction.

[0017] Based on the above technical solution, preferably, the reaction substrate is aldehyde, H2 / D2 and H2O / D2O, the pressure inside the reactor is 0.1-10MPa, the catalyst dosage is 0.001%-5%mol rhenium / substrate, the reaction temperature is 25-300℃, the stirring rate is 100-1000rpm, and the reaction time is 2-50h.

[0018] Based on the above technical solution, preferably, the aldehyde is one of formaldehyde, acetaldehyde, butyraldehyde, and veratral.

[0019] The beneficial effects of this invention are as follows:

[0020] Compared with other existing technologies, the preparation method of the present invention has a simple process and is easy to operate. Through a simple ball milling process, the active component rhenium metal is dispersed on the surface of the metal oxide support in the form of single atoms, with a high loading rate and high metal atom utilization rate.

[0021] Meanwhile, a catalytic route for aldehyde deuteration can be achieved under relatively mild conditions, and excellent deuteration selectivity can be obtained, which has good application prospects. Attached Figure Description

[0022] Figure 1 This is an electron microscope image of the RC-NO-Air catalyst prepared in Example 1 before calcination;

[0023] Figure 2 This is a high-resolution electron microscope image of the RC-NO-Air catalyst in Example 6 after the reaction; Detailed Implementation

[0024] The present invention will now be described in detail through specific embodiments, but these embodiments do not constitute a limitation on the content of the present invention. Furthermore, the embodiments only provide some conditions for achieving this objective, but do not imply that these conditions must be met to achieve this objective.

[0025] Unless otherwise specified, all materials used in the embodiments of this invention are commercially available.

[0026] Example 1

[0027] A rhenium-based catalyst, using methyl rhenium trioxide as the rhenium source and without ligands, supported on a nickel oxide (NO) support, was prepared by means of the following steps:

[0028] 1) Using methylrhenium trioxide as the rhenium source and commercially available nano-sized nickel oxide powder as the support, the mass ratio of rhenium source to nickel oxide was controlled at 0.1:1. The mixture was ball-milled at room temperature for 5 hours to obtain a nickel oxide-supported rhenium-based catalyst precursor.

[0029] 2) The catalyst precursor obtained in 1) was calcined in air for 0.5 h at a temperature of 350 °C. The resulting catalyst was labeled RC-NO-Air and had a rhenium loading of 10 wt%.

[0030] The catalyst obtained in Example 1 was characterized by aberration electron microscopy. The rhenium atoms on the surface of the prepared RC-NO-Air sample were atomically dispersed, indicating that we successfully prepared a rhenium-based single-atom catalyst.

[0031] Example 2

[0032] A rhenium-based catalyst, using methyl rhenium trioxide as the rhenium source and without ligands, supported on a nickel oxide (NO) support, was prepared by means of the following steps:

[0033] 1) Using methylrhenium trioxide as the rhenium source and commercially available nano-sized nickel oxide powder as the support, the mass ratio of rhenium source to nickel oxide was controlled at 0.1:1. The mixture was ball-milled at room temperature for 5 hours to obtain a nickel oxide-supported rhenium-based catalyst precursor.

[0034] 2) The catalyst precursor obtained in 1) was calcined in a nitrogen atmosphere for 0.5 h at a temperature of 350 °C. The resulting catalyst was labeled RC-NO-N2 with a rhenium loading of 10 wt%.

[0035] Example 3

[0036] A rhenium-based catalyst, without ligands, supported on a titanium oxide (TO) carrier and using methyl rhenium trioxide as the rhenium source, is prepared by the following steps:

[0037] 1) Using methylrhenium trioxide as the rhenium source and commercially available nano-sized titanium dioxide powder as the support, the mass ratio of rhenium source to titanium dioxide was controlled at 0.1:1. The mixture was ball-milled at room temperature for 5 hours to obtain a titanium dioxide-supported rhenium-based catalyst precursor.

[0038] 2) The catalyst precursor obtained in 1) was calcined in an air atmosphere for 0.5 h at a temperature of 350 °C. The resulting catalyst was labeled RC-TO-Air and had a rhenium loading of 10 wt%.

[0039] Example 4

[0040] A rhenium-based catalyst was prepared using methyl rhenium trioxide as the rhenium source and o-phenanthroline as the dinitrogen ligand on a nickel oxide support (NO). The preparation method includes the following steps:

[0041] 1) Under stirring conditions, o-phenanthroline was added to 10 mL of tetrahydrofuran solvent, followed by the addition of ammonium perrhenate, with a molar ratio of ammonium perrhenate to o-phenanthroline of 1:2. Stirring was continued for 2 h, and the mixture was filtered and dried under vacuum at room temperature to obtain the rhenium organometallic precursor RCPH.

[0042] 2) Using the rhenium organometallic precursor obtained in step 1) as the rhenium source and commercially available nano-iron oxide powder as the support, the mass ratio of rhenium source to metal oxide was controlled at 0.1:1. The mixture was ball-milled at room temperature for 5 hours to obtain the iron oxide-supported single-atom rhenium-based catalyst precursor RCPH-NO.

[0043] 3) The catalyst precursor RCPH-NO obtained in 2) was calcined in an air atmosphere for 0.5 h at a temperature of 350 °C. The resulting catalyst was labeled RCPH-NO-Air with a rhenium loading of 10 wt%.

[0044] Example 5

[0045] A rhenium-based catalyst was prepared using methyl rhenium trioxide as the rhenium source and o-phenanthroline as the dinitrogen ligand on a nickel oxide support (NO). The preparation method includes the following steps:

[0046] 1) Under stirring conditions, o-phenanthroline was added to 10 mL of tetrahydrofuran solvent, followed by the addition of ammonium perrhenate, with a molar ratio of ammonium perrhenate to o-phenanthroline of 1:2. Stirring was continued for 2 h, and the mixture was filtered and vacuum dried at room temperature to obtain the rhenium organometallic precursor RCPH.

[0047] 2) Using the rhenium organometallic precursor obtained in step 1) as the rhenium source and commercially available nano-iron oxide powder as the support, the mass ratio of rhenium source to metal oxide was controlled at 0.1:1. The mixture was ball-milled at room temperature for 5 hours to obtain the iron oxide-supported single-atom rhenium-based catalyst precursor RCPH-NO.

[0048] 3) The catalyst precursor RCPH-NO obtained in step 2) was calcined in a nitrogen atmosphere for 0.5 h at a temperature of 350 °C. The resulting catalyst was labeled RCPH-NO-N2 with a rhenium loading of 10 wt%.

[0049] Example 6

[0050] The catalytic performance of the catalysts in Examples 1 and 2 above for the deuteration reaction of veratral was tested.

[0051] A batch reactor was used. 50 mg of catalyst was packed into the reactor liner, and reactants veratraldehyde, H2, D2OH2O, and D2O were added. The amount of veratraldehyde was 0.4 mmol, and the amount of D2O was 2 mL. H2 was introduced and replaced three times. After replacement, hydrogen was introduced until the pressure reached 1 MPa. The reaction temperature was 130 °C, the stirring speed was 400 rpm, and the reaction time was 12 h.

[0052] The results show that the rhenium-based single-atom catalyst can catalyze the reaction process and obtain excellent yields of deuterated products. The reaction results are detailed in Table 1.

[0053] Table 1

[0054]

[0055] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. The application of a high-load single-atom rhenium-based catalyst in the deuteration reaction of aldehydes, characterized in that: The method for preparing the catalyst includes the following steps: 1) Using rhenium precursor as rhenium source and metal oxide as support, the mass ratio of rhenium source to metal oxide is controlled at 0.05-0.3:

1. The mixture is ball-milled at room temperature for 0.5-20 hours. After ball milling, the catalyst precursor powder is collected. 2) The catalyst precursor powder obtained in step 1) is calcined at high temperature to obtain a rhenium single-atom catalyst supported on a metal oxide. The rhenium precursor in step 1) includes one of ammonium perperurate, rhenium trioxide, rhenium heptaoxide, and methyl rhenium trioxide; In step 1), the metal oxide is one of titanium oxide, iron oxide, copper oxide, cerium oxide, silicon oxide, and aluminum oxide, with a size of 10-100 nm. The calcination atmosphere in step 2) is either air or nitrogen, the calcination temperature is 200-350℃, and the calcination time is 0.5-10h.

2. The application according to claim 1, characterized in that: The catalyst is loaded into the lining of the reactor, and the reaction substrate aldehyde and H2O / D2O are added. H2 / D2 is introduced to carry out the deuteration reaction. The pressure inside the reactor is 0.1-10 MPa, the catalyst dosage is 0.001%-5% mol rhenium / substrate, the reaction temperature is 25-300℃, the stirring rate is 100-1000 rpm, and the reaction time is 2-50 h.

3. The application according to claim 2, characterized in that: The reaction substrate aldehyde is one of formaldehyde, acetaldehyde, butyraldehyde, or veratral.

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