A palladium catalyst for the hydrodebromination of polyolefin base oils, method of preparation and use

Abstract

The present application relates to a kind of palladium catalyst for polyolefin base oil hydrodebromination, preparation method and application.The palladium catalyst uses nitrogen-doped activated carbon (NC) as carrier, by chemical vapor deposition method, palladium precursor is loaded on the carrier, and Pd / NC catalyst is obtained by hydrogen reduction.Relative to existing Pd / C catalyst, Pd / NC has better hydrodebromination performance, and excellent cycle performance.

Description

Technical Field

[0001] This invention relates to a metal catalyst for the hydrodebromination of polyolefin base oils, specifically a palladium catalyst, its preparation method, and its applications. Background Technology

[0002] Polyalphaolefin (PAO) lubricating oil base oil belongs to Group IV fully synthetic oils and has advantages that Group II and Group III mineral oil semi-synthetic oils cannot match, such as high viscosity index, low pour point, and good oxidation stability, thus having broad application prospects. PAO is usually obtained by oligomerization of alpha-olefins as monomers under the action of a catalyst. After polymerization, fully synthetic lubricating oils need to be further improved by catalytic hydrogenation to enhance oil quality. Hydrogenated oils do not change viscosity significantly, but their color, bromine index, and oxidation stability are greatly improved, thereby enhancing product quality. Among these, the bromine index of PAO is a key product parameter. Pd / C catalysts have excellent hydrogenation effects and are widely used in various hydrogenation reactions. However, during recycling, metal loss or metal sites being covered by reactant and / or product molecules can easily lead to deactivation. Modifying the support structure to enhance the interaction between the metal component and the support may maintain high catalytic activity while improving catalyst stability. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a palladium catalyst for hydrodebromination of polyolefin base oil, its preparation method and application, wherein the palladium catalyst has the characteristics of high stability.

[0004] To address the above technical problems, this invention first discloses a palladium catalyst for the hydrodebromination of polyolefin base oils, wherein the support for the palladium catalyst is nitrogen-doped activated carbon.

[0005] Furthermore, the nitrogen-doped activated carbon support contains 1 wt% to 5 wt% N; the Pd content in the palladium catalyst is 3 wt% to 8 wt%.

[0006] Furthermore, the nitrogen-doped activated carbon support is obtained by placing activated carbon in a quartz tube furnace, introducing NH3 / N2, and then heat-treating it at 800-1000℃ for 3-24 hours. The volume fraction of NH3 in the NH3 / N2 is 10-50%, and the nitrogen-doped activated carbon support is denoted as NC.

[0007] Furthermore, the catalyst was obtained by depositing a palladium precursor onto a nitrogen-doped activated carbon support via chemical vapor deposition, followed by reduction with hydrogen, and is denoted as Pd / NC.

[0008] Furthermore, the palladium precursor is dissolved in a solvent, and after the temperature of the quartz tube furnace reaches 200°C, it is introduced into the quartz tube furnace through N2 bubbling and deposited onto the nitrogen-doped activated carbon support.

[0009] Furthermore, the palladium precursor is bis(hexafluoroacetylacetone)palladium, and the solvent is methanol.

[0010] This invention also discloses a method for preparing the aforementioned palladium catalyst for hydrodebromination of polyolefin base oils.

[0011] The palladium catalyst was prepared by the following method.

[0012] Activated carbon is placed in a quartz tube furnace, and NH3 / N2 is introduced and then heat-treated at 800-1000℃ for 3-24 hours to obtain the NH3 / N2 with a volume fraction of 10-50%.

[0013] The palladium precursor is dissolved in a solvent, and after the temperature of the quartz tube furnace reaches 200°C, it is introduced into the quartz tube furnace through N2 bubbling and deposited onto a nitrogen-doped activated carbon support.

[0014] After deposition, the temperature of the quartz tube furnace was maintained, and hydrogen reduction was switched for 2 hours to obtain the target catalyst.

[0015] Furthermore, the palladium precursor is bis(hexafluoroacetylacetone)palladium, and the solvent is methanol. Bis(hexafluoroacetylacetone)palladium, also known as palladium(II) hexafluoroacetylacetone.

[0016] The present invention also discloses the application of the aforementioned palladium catalyst in the hydrodebromination of polyolefin base oil. PAO and the palladium catalyst are added to a high-pressure reactor, stirred, and hydrogen is introduced. The reaction temperature is 150-250°C and the reaction pressure is 1-4 MPa.

[0017] The beneficial effects of this invention are:

[0018] Compared with existing Pd / C catalysts, the advantages of this invention are: Pd / NC exhibits better debromination activity under the same reaction conditions, and the bromine index of PAO is a key product parameter. Furthermore, the catalyst's cyclic reaction performance is more stable. Detailed Implementation

[0019] Example 1

[0020] 10g of activated carbon was placed in a quartz tube furnace and heated to 800℃ under N2 protection. The gas was then switched to NH3 / N2 with a volume fraction of 10% NH3 at a flow rate of 50mL / min. The treatment was carried out for 3 hours, and the resulting sample was denoted as NC. Elemental analysis showed that the N content was approximately 2wt%.

[0021] 10g of the prepared NC was placed in a quartz tube furnace. 2.4g of palladium(II) hexafluoroacetylacetonate was dissolved in 30mL of methanol and placed in a 50mL bubbler. The bubbler temperature was 40℃, the bubbling gas was N2, and the flow rate was 20mL / min. When the quartz tube furnace reached 200℃, the bubbling gas from the bubbler was introduced into the quartz tube furnace containing NC. After the solution in the bubbler disappeared, the process continued for 0.5h. Then, pure H2 was used to continue reduction at 200℃ for 2h, with an H2 flow rate of 50mL / min, to obtain the target catalyst Pd / NC. Elemental analysis showed that the Pd content accounted for approximately 5wt% of the catalyst weight.

[0022] 100g of commercially available lubricating oil PAO20 was loaded into a 500mL autoclave reactor, along with 0.3g of Pd / NC catalyst. The autoclave reactor was heated to 150℃, H2 was introduced, the pressure was 4 MPa, and mechanical stirring was turned on. The reaction was stopped after 3 hours. The bromine index of the product met the requirements.

[0023] The hydrogenated sample after catalyst filtration and separation was subjected to bromine value analysis. The analytical method was based on the national standard GB11136-1989, "Determination of Bromine Index of Petroleum Hydrocarbon Products".

[0024] Example 2

[0025] The reaction conditions were 200°C. Other conditions were the same as in Example 1.

[0026] Example 3

[0027] The reaction conditions were: 250°C, 1 MPa. Other conditions were the same as in Example 1.

[0028] Example 4

[0029] The reaction conditions were: 250°C, 2 MPa. Other conditions were the same as in Example 1.

[0030] Example 5

[0031] The reaction conditions were 250°C. Other conditions were the same as in Example 1.

[0032] Example 6

[0033] The raw material was PAO40, and other conditions were the same as in Example 1.

[0034] Example 7

[0035] The raw material was PAO40, and other conditions were the same as in Example 2.

[0036] Example 8

[0037] The raw material was PAO40, and other conditions were the same as in Example 3.

[0038] Example 9

[0039] The raw material was PAO40, and other conditions were the same as in Example 4.

[0040] Example 10

[0041] The raw material was PAO40, and other conditions were the same as in Example 5.

[0042] Example 11

[0043] After the reaction in Example 9 was completed, the catalyst was separated and reloaded into the autoclave reactor for recycling, with the reaction conditions being the same as in Example 9.

[0044] Example 12

[0045] The catalyst was a commercial Pd / C (Pd content 5wt%). After the reaction was completed, the catalyst was separated and reloaded into the autoclave reactor for recycling. The reaction conditions were the same as in Example 9.

[0046] Example 13

[0047] The NH3 / N2 with a volume fraction of 10% was replaced with NH3 / N2 with a volume fraction of 30%. Elemental analysis showed that the resulting sample contained approximately 3 wt% N. Other conditions were the same as in Example 2.

[0048] Example 14

[0049] The NH3 / N2 with a volume fraction of 10% was replaced with NH3 / N2 with a volume fraction of 50%. Elemental analysis showed that the resulting sample contained approximately 3.5 wt% N. Other conditions were the same as in Example 2.

[0050] Example 15

[0051] The activated carbon ammonia treatment temperature was 1000℃. Elemental analysis showed that the nitrogen content of the obtained sample was approximately 1.2 wt%. Other conditions were the same as in Example 2.

[0052] Example 16

[0053] The activated carbon ammonia treatment time was 24 hours. Elemental analysis showed that the nitrogen content of the obtained sample was approximately 3.2 wt%. Other conditions were the same as in Example 2.

[0054] The reaction conditions, number of cycles, and bromine index of Examples 1-16 are shown in Table 1.

[0055] Table 1. Bromine Index of Lubricating Oil under Different Reaction Conditions and Cycle Numbers

[0056]

[0057] Example 11 uses the catalyst obtained in Example 9, showing that the bromine index remains low even after multiple cycles of Pd / NC, indicating good catalyst stability. In Comparative Example 12, the bromine index of the commercial Pd / C catalyst increases significantly with increasing cycle number, indicating that the Pd / C catalyst is more prone to deactivation. The process parameter investigations in Examples 1-10 demonstrate that higher reaction temperature and pressure result in a lower bromine index, indicating better hydrogenation performance.

Claims

1. The application of a palladium catalyst for the hydrodebromination of polyolefin base oils, characterized in that: PAO and the palladium catalyst were added to a high-pressure reactor, stirred, and hydrogen was introduced. The reaction temperature was 150~250℃ and the reaction pressure was 1~4 MPa. The palladium catalyst is supported by nitrogen-doped activated carbon; the nitrogen content in the nitrogen-doped activated carbon support is 1wt%-5wt%; the Pd content in the palladium catalyst is 3wt%-8wt%. The palladium catalyst was prepared by the following method. Activated carbon is placed in a quartz tube furnace, and NH3 / N2 is introduced and then heat-treated at 800-1000℃ for 3-24 hours to obtain the NH3 / N2 with a volume fraction of 10-50%. The palladium precursor is dissolved in a solvent, and after the temperature of the quartz tube furnace reaches 200°C, it is introduced into the quartz tube furnace through N2 bubbling and deposited onto a nitrogen-doped activated carbon support. After deposition, the temperature of the quartz tube furnace was maintained, and hydrogen reduction was switched for 2 hours to obtain the target catalyst.

2. The application of the palladium catalyst for hydrodebromination of polyolefin base oil according to claim 1 in the hydrodebromination of polyolefin base oil, characterized in that: The palladium precursor is bis(hexafluoroacetylacetone)palladium, and the solvent is methanol.

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