Supported catalyst with single crystal Pd4S as well as preparation method and application of supported catalyst

Abstract

The invention provides a method for preparing single crystal Pd4S by controlling Pd surface reconstruction and application in a hydrogenation sulfur-resistant system, Pd attached to a specific carrier, a sulfur-containing compound and a related solvent are added into a reaction kettle to react for 0.3-6 hours in a hydrogen atmosphere of 0.5-5 MPa and at a rotating speed of 700-1000 r / min, and then centrifugation is performed to obtain a catalyst with single crystal Pd4S. The method is green and pollution-free, and the synthesized catalyst is excellent in stability, good in selectivity and not prone to further poisoning and inactivation.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to a method for controlling Pd surface reconstruction to prepare single crystal Pd4S and an application thereof in a hydrogenation anti-sulfur system. Background Art

[0002] Catalytic hydrogenation is a very important process in the chemical industry, especially in the process of producing aromatic aniline compounds from aromatic nitro compounds, where precious metal catalysts are widely used because the target amine products are widely used as raw materials or intermediates for the manufacture of various high value-added fine chemicals. In particular, the hydrogenation products of some sulfur-containing aromatic nitro compounds with sulfur-containing matrix molecules, sulfur-containing anilines, are of great significance in the synthesis of various drugs such as antibiotics, pesticides, and fungicides. For example, aminothioanisole is an important intermediate for the treatment of mental illness. However, precious metal catalysts can be poisoned by sulfur-containing compounds during the hydrogenation process through strong adsorption or reaction, which hinders the dissociation of H2 and leads to a significant decrease in activity or even loss of activity. The former is a reversible poisoning, while the latter is an irreversible poisoning, that is, the d orbital of the metal and S 2- The electron perturbations form strong chemical bonds between the p orbitals of the metal and change the structure of the metal valence band by reducing the density of states near the Fermi level. These electronic perturbations inhibit the catalytic activity of the catalyst surface.

[0003] Therefore, how to improve the sulfur resistance and catalytic activity of the catalyst is an important issue that needs to be addressed. So far, transition metal phosphides and transition metal sulfides have excellent performance in hydrodesulfurization and sulfur resistance, and the most widely used sulfur-resistant catalysts in industry are NiMoS and CoMoS, which can operate under high concentrations of sulfur compounds. However, due to their poor catalytic activity and the large amount of catalyst used, their further application in hydrogenation reactions is greatly limited. For Pd-based sulfide catalysts, considering that sulfur poisoning with a strong Pd-S bond results in poor catalytic activity, Pd x S y The regeneration of this poisonous catalyst requires harsh and unsafe operating conditions (e.g., high temperatures and high-purity hydrogen are often required to break the strong Pd-S bonds), which makes this approach virtually prohibitive. x S y It is usually discarded as hazardous waste, which not only generates additional disposal costs but also causes a huge waste of precious palladium resources. However, for a stable catalyst with a single-crystalline Pd4S structure, it has abundant surface absorption and reaction sites and high electronic conductivity, which is the best catalyst among all Pd x S y Although Pd4S has relatively good performance in the catalytic field, Pd x S yThe traditional preparation method of the material generally uses H2S, Na2S or organic sulfur-containing molecules to sulfidize the palladium precursor. It has disadvantages such as high preparation temperature, high toxicity, many wastes, and long cycle. These disadvantages greatly limit the development prospects of the material. Summary of the invention

[0004] In view of the above problems, the present invention proposes a method for controlling the surface reconstruction of Pd to prepare single crystal Pd4S and its application in a hydrogenation anti-sulfur system. The design concept is to use a molecular sieve or a metal oxide as a catalyst carrier to control the surface reconstruction of Pd to prepare single crystal Pd4S, which is not easy to be deeply sulfurized.

[0005] In a first aspect, the present invention provides a supported catalyst having single-crystalline Pd4S, wherein the catalyst comprises a carrier and single-crystalline Pd4S uniformly distributed on the surface of the carrier, and the carrier is one of type A molecular sieve, type X molecular sieve, type Y molecular sieve, ZSM molecular sieve, acidic metal oxide and basic metal oxide.

[0006] In a second aspect, the present invention provides a method for preparing a supported catalyst having single crystal Pd4S, the steps of which include:

[0007] A1. Place the supported Pd-based catalyst into the reactor;

[0008] A2. adding the unsaturated sulfur-containing compound and the related solvent into the reactor, wherein the mass ratio of the supported Pd catalyst to the unsaturated sulfur-containing compound is 1:10-100;

[0009] A3. After the reactor is sealed, the reaction temperature is 80-200 ° C, the pressure is 0.5-5MPa of H2 atmosphere, and the speed is 700-1000r / min for 0.3-6h;

[0010] A4. After the reaction is completed, the catalyst is filtered or centrifuged to obtain a catalyst having single crystal Pd4S after surface reconstruction.

[0011] Preferably, the carrier of the supported Pd-based catalyst is one of A-type molecular sieve, X-type molecular sieve, Y-type molecular sieve, ZSM-type molecular sieve, acidic metal oxide and basic metal oxide.

[0012] Preferably, the carrier of the supported Pd-based catalyst is one of ZSM-5, SAPO-34, MCM-41, TiO2, ZrO2, CeO2, and γ-Al2O3.

[0013] Preferably, the Pd loading in the supported Pd-based catalyst is 0.5-10 wt%.

[0014] Preferably, the unsaturated sulfur-containing compound in step A2 is one of the following compounds:

[0015]

[0016] Preferably, the reaction temperature in step A3 is 90-150°C, the H2 pressure is 1-3MPa, and the rotation speed is 1000r·min -1 , the reaction time is 0.5-1.5h.

[0017] Preferably, the mass ratio of the supported Pd catalyst to the unsaturated sulfur-containing compound is 1:20-50, and the mass ratio of the relevant solvent to the supported Pd catalyst is 5-15:1.

[0018] In a second aspect, the present invention proposes a method for controlling Pd surface reconstruction to prepare single crystal Pd4S in a hydrogenation anti-sulfur system, the steps of which include:

[0019] B1. The unsaturated olefin sulfur-containing compound or sulfur-containing aromatic nitro compound, molecular sieve or metal oxide-supported single crystal Pd4S catalyst powder and solvent were added to a 250mL reactor;

[0020] B2. Conducting continuous hydrogenation reaction under a hydrogen atmosphere to generate hydrogenation products.

[0021] Preferably, a 250 mL reactor is used in step B1, the mass ratio of single crystal Pd4S to sulfur-containing compound is 1:10-100, the mass ratio of related solvent to supported Pd catalyst is 2-50:1; the related solvent is one of methanol, ethanol, toluene, N,N-dimethylformamide, and tetrahydrofuran;

[0022] Preferably, in step B2, the reactor is sealed and reacted for 0.3-6h in a H2 atmosphere at a reaction temperature of 80-200°C, a pressure of 0.5-5MPa, and a rotation speed of 700-1000r / min.

[0023] The preparation method of the supported Pd-based catalyst in step A1 can be prepared by a deposition precipitation method, an impregnation method, a gel method and a hydrothermal method; the most preferred method is a deposition precipitation method, and the preparation method comprises the following steps:

[0024] Ultrasonicate or stir a certain amount of Pd precursor solution to make it uniformly dispersed in the solvent. Introduce a certain amount of molecular sieve or metal oxide carrier into the precursor solution, stir at 35-85°C for 2-8h, add a precipitant to adjust the solution pH to about 8-10, precipitate and age for 1-6h, then filter and wash. After drying and grinding, calcine in an inert atmosphere in a tube furnace for 1-3h, then switch to 5% H2 / Ar mixed gas for reduction for 2-4h, and finally obtain a supported Pd-based catalyst.

[0025] The beneficial effects of the present invention are:

[0026] 1) The present invention uses a simple method to in-situ prepare a catalyst having a single crystal Pd4S structure, and the preparation method is green and pollution-free; while the traditional method has the disadvantages of high preparation temperature, high toxicity, high waste, high waste gas and long cycle.

[0027] 2) The present invention adopts a molecular sieve or metal oxide carrier that has a stronger interaction with Pd metal nanoparticles. Compared with traditional activated carbon carriers, the synthesized metal sulfide has the advantages of strong stability and high controllability; in addition, the use of an acidic carrier increases the sulfur resistance of the catalyst.

[0028] 3) The catalyst prepared by the present invention has a selectivity of more than 99.9%, strong stability, and no deactivation occurs after continuous application for more than 20 reactions. Compared with metal Pd, the activity has almost no decrease. The time for catalytic hydrogenation of sulfur-containing compounds is greatly shortened, and the production cost is greatly saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a scanning electron microscope image of a Pd4S / ZSM-5 catalyst prepared by a method for preparing single-crystal Pd4S by controlling Pd surface reconstruction according to the present invention.

[0030] Figure 2 It is an X-ray diffraction spectrum of a Pd4S / ZSM-5 catalyst prepared by a method for preparing single-crystal Pd4S by controlling Pd surface reconstruction of the present invention.

[0031] Figure 3 It is a comparison chart of the stability evaluation of the catalysts Pd4S / ZSM-5 and Pd / C prepared in Example 1 at low conversion rate. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments, but the scope of protection of the present invention is not limited to the described scope.

[0033] Embodiment 1

[0034] Dissolve 2.1mL of a precursor solution of H2PdCl4 solution with a concentration of 0.05g / mL Pd in ​​100mL of deionized water and stir at 450r / min for 1h to make it uniformly dispersed in the solvent. Introduce 2g of molecular sieve (ZSM-5) into the above precursor solution, stir at 60°C for 3h, add 1mol / LNaOH aqueous solution to adjust the solution pH to about 9, precipitate and age for 2h, then filter and wash. Dry the catalyst at 110°C for 8h, grind it, calcine it at 400°C in a tubular furnace under N2 atmosphere for 2h, and then switch to 5% H2 / Ar mixed gas for reduction for 2h to finally obtain Pd / ZSM-5 catalyst.

[0035] Take 10g 4-nitroanisole and 80mL toluene in a 250mL reactor, and add 0.3g Pd / ZSM-5 catalyst. After sealing the reactor, replace the air in the reactor with N2 repeatedly to check the airtightness of the reactor. Switch to hydrogen atmosphere and react at 130℃, with the mechanical stirring rate controlled at 1000r·min -1 , the H2 pressure was controlled at 3MPa, the reaction lasted for 1 hour, and then the mixture was naturally cooled, filtered, and dried in a 110°C forced air drying oven for 6 hours to obtain the prepared Pd4S / ZSM-5 catalyst. The prepared catalyst was reacted again according to the same procedure, and the hydrogenation product was quantitatively analyzed by an Angilent 7890B gas chromatograph. After 0.8 hours of reaction, the conversion rate of the raw material was determined to be 99.9%, and the selectivity of the target product was 99.6%.

[0036] Figure 1 This is a scanning electron microscope image of the Pd4S / ZSM-5 catalyst synthesized in this example. It can be seen that single crystal Pd4S is uniformly attached to the surface of the ZSM-5 carrier. Figure 2 It is the X-ray diffraction spectrum of the Pd4S / ZSM-5 catalyst synthesized in this example.

[0037] Embodiment 2 to Embodiment 9

[0038] Dissolve 2.1mL of a precursor solution of H2PdCl4 solution with a concentration of 0.05g / mL Pd in ​​100mL of deionized water and stir at 450r / min for 1h to make it uniformly dispersed in the solvent. Introduce 2g of molecular sieve (ZSM-5) into the above precursor solution, stir at 60°C for 3h, add 1mol / LNaOH aqueous solution to adjust the solution pH to about 9, precipitate and age for 2h, then filter and wash. Dry the catalyst at 110°C for 8h, grind it, calcine it at 400°C in a tubular furnace under N2 atmosphere for 2h, and then switch to 5% H2 / Ar mixed gas for reduction for 2h to finally obtain Pd / ZSM-5 catalyst.

[0039] Take 10g of one of the following sulfur-containing compounds (Ⅰ-biotin precursor structure, Ⅱ-(2-[β(2-thienyl)vinyl]benzoic acid, Ⅲ-1-nitrodibenzothiophene, Ⅴ-2-nitro-4-(propylthio)aniline, Ⅵ-4-nitrobenzenethiol, Ⅶ-3,3'-sulfonylbisnitrobenzene, Ⅷ-4-nitrophenylbenzene sulfide, Ⅸ-2-nitroanisole) and 80mL toluene and place it in a 250mL reactor, and add 0.3g Pd / ZSM-5 catalyst. After sealing the reactor, repeatedly replace the air in the reactor with N2 to check the airtightness of the reactor. Switch to hydrogen atmosphere and react at 130℃, and the mechanical stirring rate is controlled at 1000r·min -1, H2 pressure was controlled at 3MPa, the reaction lasted for 1 hour, then the mixture was cooled naturally, filtered and dried in a 110°C forced air drying oven for 6 hours to obtain the prepared Pd4S / ZSM-5 catalyst. The prepared catalyst was reacted again according to the same procedure, and the hydrogenation product was quantitatively analyzed by an Angilent7890B gas chromatograph. The reaction results are shown in Table 1 below.

[0040] Table 1 - Evaluation of the preparation of Pd4S / ZSM-5 under different reaction substrates.

[0041]

[0042] Embodiment 10 to Embodiment 18

[0043] Dissolve 2.1mL of a precursor solution of H2PdCl4 solution with a concentration of 0.05g / mL Pd in ​​100mL of deionized water and stir at 450r / min for 1h to make it uniformly dispersed in the solvent. Introduce 2g of molecular sieve (ZSM-5) into the above precursor solution, stir at 60°C for 3h, add 1mol / LNaOH aqueous solution to adjust the solution pH to about 9, precipitate and age for 2h, then filter and wash. Dry the catalyst at 110°C for 8h, grind it, calcine it at 400°C in a tubular furnace under N2 atmosphere for 2h, and then switch to 5% H2 / Ar mixed gas for reduction for 2h to finally obtain Pd / ZSM-5 catalyst.

[0044] Take 10g 4-nitroanisole and 80mL toluene in a 250mL reactor, and add 0.3g of pre-prepared Pd / ZSM-5 catalyst. After sealing the reactor, repeatedly replace the air in the reactor with N2 to check the airtightness of the reactor. Switch to hydrogen atmosphere and react at different temperatures. The mechanical stirring rate is controlled at 1000r·min -1 , the H2 pressure was controlled at 3MPa, the reaction lasted for 1 hour, and then the mixture was cooled naturally, filtered, and dried in a 110°C forced air drying oven for 6 hours to obtain the prepared Pd4S / ZSM-5 catalyst. The prepared catalyst was reacted again according to the same procedure, and the hydrogenation product was quantitatively analyzed by an Angilent 7890B gas chromatograph. The reaction results are shown in Table 2 below.

[0045] Table 2 - Evaluation of the preparation of Pd4S / ZSM-5 at different reaction temperatures.

[0046]

[0047] Embodiment 19 to Embodiment 27

[0048] Take 10g 4-nitroanisole and 80mL toluene in a 250mL reactor, and add 0.3g Pd4S catalyst loaded with different carriers. After sealing the reactor, repeatedly replace the air in the reactor with N2 to check the airtightness of the reactor. Switch to hydrogen atmosphere and react at 130℃, with the mechanical stirring rate controlled at 1000r·min -1 The H2 pressure was controlled at 3 MPa. After the reaction lasted for 1 hour, the hydrogenation product was quantitatively analyzed by Angilent 7890B gas chromatograph. The reaction results are shown in Table 3 below.

[0049] Table 3 - Evaluation of different catalyst supports for loading Pd4S.

[0050]

[0051]

[0052] Embodiment 28

[0053] Take 10g 4-nitroanisole and 80mL toluene in a 250mL reactor, and add 0.3g Pd4S / ZSM-5 catalyst prepared in Example 1. After sealing the reactor, replace the air in the reactor with N2 repeatedly to check the airtightness of the reactor. Switch to hydrogen atmosphere and react at 130℃, with the mechanical stirring rate controlled at 1000r·min -1 The H2 pressure was controlled at 3 MPa. After the reaction lasted for 1 hour, the hydrogenation product was quantitatively analyzed by Angilent 7890B gas chromatograph. The reaction was repeated according to the same procedure, and the hydrogenation product was quantitatively analyzed by Angilent 7890B gas chromatograph. This was repeated 20 times.

[0054] As a comparative example, 10 g of 4-nitroanisole and 80 mL of toluene were placed in a 250 mL reactor, and 0.3 g of Pd / C catalyst was added. After sealing the reactor, the air in the reactor was repeatedly replaced with N2 to check the air tightness of the reactor. The reaction was switched to a hydrogen atmosphere at 130 °C, and the mechanical stirring rate was controlled at 1000 r / min. -1 The H2 pressure was controlled at 3MPa. After the reaction lasted for 1 hour, the mixture was cooled naturally, filtered and dried in a blast drying oven at 110°C for 6 hours. Due to the insufficient stability of Pd on the carbon support, it could not be stably sulfurized into Pd4S single crystals to obtain the prepared Pd x S y / C catalyst. The prepared catalyst was reacted again according to the same procedure, and the hydrogenation product was quantitatively analyzed by Angilent 7890B gas chromatograph. The catalyst lost its activity after 7 times of reaction.

[0055] The results of the two comparative experiments in Example 28 are as follows: Figure 3 As shown, it can be seen that Pd x S y / C has almost no activity after six applications; while the reaction rate of Pd4S / ZSM-5 catalyst remains basically stable at low conversion rate, which shows that the Pd4S / ZSM-5 catalyst prepared by Pd / ZSM-5 in Example 1 is better than that prepared by Pd / C. x S y / C catalyst has high stability and activity.

Claims

1. A supported catalyst having single crystal Pd4S, characterized in that: The invention comprises a carrier and single crystal Pd4S uniformly distributed on the surface of the carrier, wherein the carrier is one of A-type molecular sieve, X-type molecular sieve, Y-type molecular sieve, ZSM-type molecular sieve, acidic metal oxide and alkaline metal oxide.

2. A method for preparing a supported catalyst having single crystal Pd4S according to claim 1, comprising the steps of: A1. Place the supported Pd-based catalyst into the reactor; A2. adding the unsaturated sulfur-containing compound and the related solvent into the reactor, wherein the mass ratio of the supported Pd catalyst to the unsaturated sulfur-containing compound is 1:10-100; A3. After the reactor is sealed, the reaction temperature is 80-200 ° C, the pressure is 0.5-5MPa of H2 atmosphere, and the speed is 700-1000r / min for 0.3-6h; A4. After the reaction is completed, the catalyst is filtered or centrifuged to obtain a catalyst having single crystal Pd4S after surface reconstruction.

3. A method for preparing a supported catalyst having single crystal Pd4S according to claim 2, characterized in that: The carrier of the supported Pd-based catalyst is one of A-type molecular sieve, X-type molecular sieve, Y-type molecular sieve, ZSM-type molecular sieve, acidic metal oxide and basic metal oxide.

4. The method for preparing a supported catalyst having single crystal Pd4S according to claim 3, characterized in that: The carrier of the supported Pd-based catalyst is one of ZSM-5, SAPO-34, MCM-41, TiO2, ZrO2, CeO2, and γ-Al2O3.

5. The method for preparing a supported catalyst having single crystal Pd4S according to claim 2, characterized in that: The relevant solvent is one of methanol, ethanol, toluene, N,N-dimethylformamide, and tetrahydrofuran.

6. The method for preparing a supported catalyst having single crystal Pd4S according to claim 2, characterized in that: The Pd loading in the supported Pd-based catalyst is 0.5-10 wt%.

7. The method for preparing a supported catalyst having single crystal Pd4S according to claim 2, characterized in that: The unsaturated sulfur-containing compound in step A2 is one of the following compounds:

8. The method for preparing a supported catalyst having single crystal Pd4S according to claim 2, characterized in that: In step A3, the reaction temperature is 90-150°C, the H2 pressure is 1-3MPa, and the rotation speed is 1000r·min -1 , the reaction time is 0.5-1.5h.

9. The method for preparing a supported catalyst having single crystal Pd4S according to claim 2, characterized in that: The mass ratio of the supported Pd catalyst to the unsaturated sulfur-containing compound is 1:20-50, and the mass ratio of the relevant solvent to the supported Pd catalyst is 5-15:

1.

10. The use of a supported catalyst having single crystal Pd4S according to claim 1 in a hydrogenation sulfur-resistant system, comprising the steps of: B1. The unsaturated olefin sulfur-containing compound or sulfur-containing aromatic nitro compound, a supported catalyst powder having a single crystal Pd4S and a solvent were added to a 250mL reactor; B2. Conducting continuous hydrogenation reaction under a hydrogen atmosphere to generate hydrogenation products.

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