A rare earth doped phosphotungstic acid structure catalyst, a preparation method and application thereof

Abstract

This invention proposes a rare-earth-doped phosphotungstic acid (PPA) structural catalyst, its preparation method, and its application. The preparation method includes: preparing rare-earth La and / or Ce-modified PPA active components via ion exchange; using monolithic 3D stainless steel metal fibers as a structural carrier; cutting and winding stainless steel θ-ring packing materials, mimicking the structure of θ-ring packing materials used in distillation, into a θ-ring-like hollow structure to obtain a 3D stainless steel metal fiber θ-ring packing; and then loading the rare-earth La and / or Ce-modified PPA active components onto the 3D stainless steel metal fiber θ-ring packing using a sol-gel / impregnation method to obtain the rare-earth La and / or Ce-doped PPA structural catalyst. The rare-earth-doped PPA structural catalyst prepared by this invention can be applied to chemical process intensification technologies such as reactive distillation to improve the conversion efficiency of biodiesel and oxidative desulfurization.

Description

Technical Field

[0001] This invention relates to the field of solid acid structure catalyst preparation technology, and particularly to a rare earth-doped phosphotungstic acid structure catalyst, its preparation method, and its application. Background Technology

[0002] Phosphotungstic acid (H3PW) 12 O 40 ·nH2O (HPW) is an excellent solid acid catalyst and can also be used as an oxidation reaction catalyst. It has the advantages of large molecular volume, strong proton and electron storage and transport capacity, high thermal stability, high proton acidity, and no secondary pollution. It is widely used in acid catalysis and catalytic desulfurization processes.

[0003] However, although phosphotungstic acid has relatively high acidity and oxidizing properties, its small specific surface area prevents it from fully exhibiting its catalytic activity. Problems such as easy corrosion of equipment, difficulty in product recovery, and difficulty in separating it from the reaction system limit its application in industrial catalysis.

[0004] To address these issues, phosphotungstic acid is typically modified with metal or ionic liquid groups to improve its acidity and stability. Porous materials such as molecular sieves and carbon nanotubes are used as catalyst supports to increase the specific surface area and dispersion of the catalyst. Doping with rare earth elements La and Ce, and metallic Ag, synergistically modifies phosphotungstic acid. The electron-withdrawing effect of La or Ce alters the charge imbalance, preserving the properties of phosphotungstic acid while improving its stability in aqueous phase, forming a novel solid acid catalyst dominated by Lewis acidic active sites. A monolithic metal fiber matrix serves as the catalyst support layer. The three-dimensional network structure of the fibers features high porosity, open pores, and a large specific surface area, which is beneficial for mass and heat transfer. It also acts as a micro-stirrer, facilitating micron-scale segmentation and rapid mixing of fluids. To meet the requirements of phosphotungstic acid catalysts at the engineering scale, catalyst engineering fully considers the influence and constraints of the catalyst's macroscopic structure on the internal flow and heat / mass transfer characteristics of reactors in chemical processes, thereby facilitating catalyst optimization and industrial application. However, in the existing technology, due to the molecular structure characteristics of phosphotungstic acid, it is difficult to process it according to the microreactor structure. In terms of macroscopic structure design, the active component of phosphotungstic acid is difficult to be firmly loaded on the metal fiber structure carrier, which makes the design and construction of phosphotungstic acid structure catalysts difficult and cannot be effectively applied to process enhancement technologies such as reactive distillation. Summary of the Invention

[0005] In view of the above situation, the main objective of the present invention is to provide a rare earth-doped phosphotungstic acid structure catalyst, its preparation method and application, in order to solve the above-mentioned technical problems.

[0006] This invention proposes a rare earth-doped phosphotungstic acid structured catalyst, comprising 3D stainless steel metal fibers and rare earth La and / or Ce modified doped phosphotungstic acid active components. The catalyst uses a stainless steel θ mesh ring packing made of integral 3D stainless steel metal fibers as the structural support, and the rare earth La and / or Ce modified doped phosphotungstic acid active components are loaded on the 3D stainless steel metal fibers.

[0007] This invention also proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0008] Weigh phosphotungstic acid powder and add first deionized water, then stir at room temperature to prepare phosphotungstic acid solution;

[0009] Weigh out La(NO3)3·6H2O and / or Ce(NO3)3·6H2O, then weigh out AgNO3. Add the weighed La(NO3)3·6H2O and / or Ce(NO3)3·6H2O and AgNO3 to the second deionized water and stir at room temperature to prepare a metal salt solution.

[0010] A metal salt solution was slowly added dropwise to a phosphotungstic acid solution and mixed evenly to obtain a metal-modified phosphotungstic acid mixed solution. The metal-modified phosphotungstic acid mixed solution was stirred and reacted at room temperature. After the reaction was complete, a mixed solution of rare earth La and Ce modified and doped phosphotungstic acid active components was obtained.

[0011] Weigh out C8H 20 O4Si was slowly added dropwise to a mixed solution of rare earth La and Ce modified and doped phosphotungstic acid active components. After being stirred evenly and left to stand in the dark, a dispersion solution of rare earth La and Ce modified and doped phosphotungstic acid and SiO2 was obtained.

[0012] Using 3D stainless steel metal fiber as the structural carrier, the stainless steel θ mesh ring packing is cut and wound into a θ ring hollow structure, imitating the structure of the stainless steel θ mesh ring packing used in distillation, to obtain 3D stainless steel metal fiber θ mesh ring packing.

[0013] The 3D stainless steel metal fiber θ mesh ring packing was immersed in a dispersion solution and ultrasonically vibrated. After ultrasonic vibration treatment, it was dried. After several cycles of ultrasonic vibration treatment and drying treatment, it was calcined. After calcination, a rare earth-doped phosphotungstic acid structure catalyst was obtained.

[0014] This invention also proposes an application of a rare earth-doped phosphotungstic acid structure catalyst. The rare earth-doped phosphotungstic acid structure catalyst prepared by the above-mentioned method is used to catalyze esterification to prepare biodiesel or to remove thiophene compounds from diesel fuel through oxidative desulfurization.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. This invention selects 3D network structure stainless steel metal fibers, which enhance heat / mass transfer and optimize the fluid flow properties of the catalytic bed, as a microstructure carrier. The three-dimensional network structure of the fibers has characteristics such as high porosity, open pore structure, and large specific surface area, which is beneficial to mass and heat transfer, and also acts as a micro-stirrer, which is conducive to the micron-scale segmentation and rapid mixing of fluids; utilizing C8H 20 The silica sol obtained by O4Si hydrolysis confines the phosphotungstic acid active component to the surface of stainless steel fibers, and the microreactor design of the phosphotungstic acid active component is realized by using the stainless steel fiber structure as a substrate template.

[0017] 2. This invention utilizes the doping modification of rare earth elements La, Ce, and metal Ag to improve the stability of phosphotungstic acid in aqueous solution while retaining the acidity and oxidizing properties of the active components of phosphotungstic acid. The active components of phosphotungstic acid are firmly loaded on the metal fiber structure support. The catalyst preparation process is simple to operate, has low production cost, simple production process, and can be prepared in large-scale macroscopic batches.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments of the invention. Attached Figure Description

[0019] Figure 1 SEM images of the samples obtained in Examples 3, 6, and 9;

[0020] Figure 2 The XRD patterns of the sample obtained in Example 9 and the catalyst composition are shown below.

[0021] Figure 3 The NH3-TPD diagrams are for the samples obtained in Examples 3, 6, and 9.

[0022] Figure 4 This is a schematic diagram illustrating the performance of the catalysts prepared in Examples 3, 6, and 9 for catalytic esterification to produce biodiesel.

[0023] Figure 5 This is a schematic diagram showing the oxidative desulfurization performance of the catalysts prepared in Examples 3, 6, and 9.

[0024] Figure 6 This is a schematic diagram of the activity of the sample with the strongest stability and acid catalytic activity among the samples obtained in Examples 3, 6 and 9 in the process of preparing methyl propionate by reactive distillation. Detailed Implementation

[0025] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0026] These and other aspects of the embodiments of the present invention will become clear from the following description and accompanying drawings. In these descriptions and drawings, some specific embodiments of the present invention are specifically disclosed to illustrate some ways of implementing the principles of the embodiments of the present invention; however, it should be understood that the scope of the embodiments of the present invention is not limited thereto.

[0027] Example 1

[0028] This embodiment proposes a rare earth-doped phosphotungstic acid structure catalyst, comprising 3D stainless steel metal fibers and rare earth La and / or Ce modified doped phosphotungstic acid active components. The 3D stainless steel metal fiber material is used as a stainless steel θ mesh ring packing as a structural support, and the rare earth La and / or Ce modified doped phosphotungstic acid active components are loaded on the 3D stainless steel metal fibers.

[0029] Example 2

[0030] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0031] Rare earth-modified doped phosphotungstic acid active components were prepared using an ion exchange method.

[0032] First, 1g of phosphotungstic acid powder was weighed and added to 10ml of deionized water. The mixture was stirred at room temperature to prepare a phosphotungstic acid solution. Then, 0.1g of AgNO3 and 0.05g of Ce(NO3)3·6H2O were weighed and added to 5ml of deionized water. The mixture was stirred at room temperature to prepare a metal salt solution. The prepared phosphotungstic acid solution and metal salt solution were colorless and transparent. When the metal salt solution was slowly added dropwise to the phosphotungstic acid solution, it changed from colorless to orange-yellow. The metal salt solution was slowly added dropwise to the phosphotungstic acid solution and mixed evenly to obtain a metal-modified phosphotungstic acid mixed solution. The mixture was stirred dropwise at room temperature for 0.5h until the reaction was complete to obtain a rare earth Ce-modified doped phosphotungstic acid active component mixed solution.

[0033] Rare earth Ce-doped phosphotungstic acid structured catalysts were prepared using a sol-gel / impregnation method.

[0034] According to C8H 20 The mass ratio of O4Si to rare earth Ce-modified phosphotungstic acid active component in the mixed solution is 0.5:1. C8H... 20O4Si was slowly added dropwise to the mixed solution of rare earth Ce-modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 1 hour, the mixture was allowed to stand in the dark for 5 hours to obtain a dispersion solution of rare earth Ce-modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth Ce-modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 0.1 hours. Then, it was dried in a drying oven at 100°C for 2 hours. The coating and drying process was repeated 3 times. Finally, the mixture was heated to 100°C in a muffle furnace and heated continuously for 3 hours to obtain the rare earth Ce-doped phosphotungstic acid structural catalyst (Ce-Ag-PW-SiO2 / SS-fibe).

[0035] Example 3

[0036] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0037] Rare earth-modified doped phosphotungstic acid active components were prepared using an ion exchange method.

[0038] First, weigh 2g of phosphotungstic acid powder and add it to 10ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.15g of AgNO3 and 0.1g of Ce(NO3)3·6H2O and add them to 10ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the solution at room temperature for 1 hour until the reaction is complete to obtain a rare earth Ce-modified doped phosphotungstic acid active component mixed solution.

[0039] Rare earth Ce-doped phosphotungstic acid structured catalysts were prepared using a sol-gel / impregnation method.

[0040] According to C8H 20 The mass ratio of O4Si to rare earth Ce-modified and doped phosphotungstic acid active component in the mixed solution is 1:1. C8H... 20O4Si was slowly added dropwise to the mixed solution of rare earth Ce-modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 2 hours, the mixture was allowed to stand in the dark for 12 hours to obtain a dispersion solution of rare earth Ce-modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth Ce-modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 0.25 hours. Then, it was dried in a drying oven at 100°C for 2 hours. The coating and drying process was repeated 4 times. Finally, the mixture was heated to 200°C in a muffle furnace and heated continuously for 4 hours to obtain the rare earth Ce-doped phosphotungstic acid structural catalyst (Ce-Ag-PW-SiO2 / SS-fibe).

[0041] Example 4

[0042] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0043] Rare earth-modified doped phosphotungstic acid active components were prepared using an ion exchange method.

[0044] First, weigh 3g of phosphotungstic acid powder and add it to 30ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.5g of AgNO3 and 0.5g of Ce(NO3)3·6H2O and add them to 30ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the metal salt solution at room temperature for 1 hour until the reaction is complete to obtain a rare earth Ce-modified doped phosphotungstic acid active component mixed solution.

[0045] Rare earth Ce-doped phosphotungstic acid structured catalysts were prepared using a sol-gel / impregnation method.

[0046] According to C8H 20 The mass ratio of O4Si to rare earth Ce-modified and doped phosphotungstic acid active component in the mixed solution is 4:1. C8H... 20O4Si was slowly added dropwise to the rare earth Ce-modified doped phosphotungstic acid active component mixed solution prepared in step one. After stirring uniformly for 2 hours, the mixture was allowed to stand in the dark for 12 hours to obtain a dispersion solution composed of rare earth Ce-modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution composed of rare earth Ce-modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 1 hour. Then, it was dried in a drying oven at 100°C for 2 hours. The coating and drying operation was repeated 6 times. Finally, it was heated to 400°C in a muffle furnace and heated continuously for 6 hours to obtain the rare earth Ce-doped phosphotungstic acid structural catalyst (Ce-Ag-PW-SiO2 / SS-fibe).

[0047] Example 5

[0048] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0049] Rare earth La-modified doped phosphotungstic acid active component was prepared by ion exchange method:

[0050] First, weigh 1g of phosphotungstic acid powder and add it to 10ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.1g of AgNO3 and 0.05g of La(NO3)3·6H2O and add them to 5ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the metal salt solution at room temperature for 0.5h until the reaction is complete to obtain a rare earth La-modified doped phosphotungstic acid active component mixed solution.

[0051] Rare earth La-doped phosphotungstic acid structured catalysts were prepared using a sol-gel / impregnation method.

[0052] According to C8H 20 The mass ratio of O4Si to rare earth La-modified doped phosphotungstic acid active component in the mixed solution is 0.5:1. C8H... 20O4Si was slowly added dropwise to the mixed solution of rare earth La-modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 1 hour, the mixture was allowed to stand in the dark for 5 hours to obtain a dispersion solution of rare earth La-modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth La-modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 0.1 hours. Then, it was dried in a drying oven at 100°C for 2 hours. The coating and drying process was repeated 3 times. Finally, the mixture was heated to 100°C in a muffle furnace and heated continuously for 3 hours to obtain the rare earth La-doped phosphotungstic acid structural catalyst (La-Ag-PW-SiO2 / SS-fibe).

[0053] Example 6

[0054] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0055] Rare earth La-modified doped phosphotungstic acid active component was prepared by ion exchange method:

[0056] First, weigh 2g of phosphotungstic acid powder and add it to 10ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.1g of AgNO3 and 0.2g of La(NO3)3·6H2O and add them to 10ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the metal salt solution at room temperature for 2 hours until the reaction is complete to obtain a rare earth La-modified doped phosphotungstic acid active component mixed solution.

[0057] Rare earth La-doped phosphotungstic acid structured catalysts were prepared using a sol-gel / impregnation method.

[0058] According to C8H 20 The mass ratio of O4Si to rare earth La-modified doped phosphotungstic acid active component in the mixed solution is 0.75:1. C8H... 20O4Si was slowly added dropwise to the mixed solution of rare earth La-modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 2 hours, the mixture was allowed to stand in the dark for 12 hours to obtain a dispersion solution of rare earth La-modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth La-modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 0.25 hours. Then, it was dried in a drying oven at 100°C for 2 hours. The coating and drying operation was repeated 4 times. Finally, it was heated to 200°C in a muffle furnace and heated continuously for 4 hours to obtain the rare earth La-doped phosphotungstic acid structural catalyst (La-Ag-PW-SiO2 / SS-fibe).

[0059] Example 7

[0060] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0061] Rare earth La-modified doped phosphotungstic acid active component was prepared by ion exchange method:

[0062] First, weigh 3g of phosphotungstic acid powder and add it to 30ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.5g of AgNO3 and 0.5g of La(NO3)3·6H2O and add them to 30ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the metal salt solution at room temperature for 1 hour until the reaction is complete to obtain a rare earth La-modified doped phosphotungstic acid active component mixed solution.

[0063] Rare earth La-doped phosphotungstic acid structured catalysts were prepared using a sol-gel / impregnation method.

[0064] According to C8H 20 The mass ratio of O4Si to rare earth La-modified doped phosphotungstic acid active component in the mixed solution is 4:1. C8H... 20O4Si was slowly added dropwise to the mixed solution of rare earth La-modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 2 hours, the mixture was allowed to stand in the dark for 12 hours to obtain a dispersion solution of rare earth La-modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth La-modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 1 hour. Then, it was dried in a drying oven at 100°C for 2 hours. The coating and drying operation was repeated 6 times. Finally, it was heated to 400°C in a muffle furnace and heated continuously for 6 hours to obtain the rare earth La-doped phosphotungstic acid structural catalyst (La-Ag-PW-SiO2 / SS-fibe).

[0065] Example 8

[0066] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0067] Preparation of rare-earth La and Ce modified and doped phosphotungstic acid active components by ion exchange method:

[0068] First, weigh 1g of phosphotungstic acid powder and add it to 10ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.1g of AgNO3, 0.05g of La(NO3)3·6H2O, and 0.05g of Ce(NO3)3·6H2O and add them to 5ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the metal salt solution at room temperature for 0.5h until the reaction is complete to obtain a mixed solution of rare earth La and Ce modified and doped phosphotungstic acid active components.

[0069] Preparation of rare earth-doped phosphotungstic acid structured catalysts by sol-gel / impregnation method:

[0070] According to C8H 20 The mass ratio of O4Si to rare earth La and Ce modified and doped phosphotungstic acid active components is 0.5:1. C8H... 20O4Si was slowly added dropwise to the mixed solution of rare earth La and Ce modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 1 hour, the mixture was allowed to stand in the dark for 5 hours to obtain a dispersion solution of rare earth La and Ce modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth La and Ce modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 0.1 hours. Then, it was dried in a drying oven at 100°C for 2 hours. After repeating the coating and drying operation 3 times, it was heated to 100°C in a muffle furnace and heated continuously for 3 hours to obtain the rare earth doped phosphotungstic acid structural catalyst (La-Ce-Ag-PW-SiO2 / SS-fibe).

[0071] Example 9

[0072] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0073] Preparation of rare-earth La and Ce modified and doped phosphotungstic acid active components by ion exchange method:

[0074] First, weigh 2g of phosphotungstic acid powder and add it to 10ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.1g of AgNO3, 0.1g of La(NO3)3·6H2O and 0.1g of Ce(NO3)3·6H2O and add them to 10ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the metal salt solution at room temperature for 1 hour until the reaction is complete to obtain a mixed solution of rare earth La and Ce modified and doped phosphotungstic acid active components.

[0075] Preparation of rare earth-doped phosphotungstic acid structured catalysts by sol-gel / impregnation method:

[0076] According to C8H 20 The mass ratio of O4Si to rare earth La and Ce modified and doped phosphotungstic acid active component was 1:1. C8H was weighed out. 20O4Si was slowly added dropwise to the mixed solution of rare earth La and Ce modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 2 hours, the mixture was allowed to stand in the dark for 12 hours to obtain a dispersion solution of rare earth La and Ce modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth La and Ce modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 0.25 hours. Then, it was dried in a drying oven at 100°C for 2 hours. After repeating the coating and drying operation 4 times, it was heated to 200°C in a muffle furnace and heated continuously for 4 hours to obtain the rare earth doped phosphotungstic acid structural catalyst (La-Ce-Ag-PW-SiO2 / SS-fibe).

[0077] Example 10

[0078] This embodiment proposes a method for preparing a rare earth-doped phosphotungstic acid structured catalyst, which is used to prepare the above-mentioned rare earth-doped phosphotungstic acid structured catalyst. The method includes the following steps:

[0079] Preparation of rare-earth La and Ce modified and doped phosphotungstic acid active components by ion exchange method:

[0080] First, weigh 3g of phosphotungstic acid powder and add it to 30ml of deionized water. Stir at room temperature to prepare a phosphotungstic acid solution. Then, weigh 0.5g of AgNO3, 0.5g of La(NO3)3·6H2O and 0.5g of Ce(NO3)3·6H2O and add them to 30ml of deionized water. Stir at room temperature to prepare a metal salt solution. Slowly add the metal salt solution to the phosphotungstic acid solution and mix evenly to obtain a metal-modified phosphotungstic acid mixed solution. Stir while adding the metal salt solution at room temperature for 1 hour until the reaction is complete to obtain a mixed solution of rare earth La and Ce modified and doped phosphotungstic acid active components.

[0081] Preparation of rare earth-doped phosphotungstic acid structured catalysts by sol-gel / impregnation method:

[0082] According to C8H 20 The mass ratio of O4Si to rare earth La and Ce modified and doped phosphotungstic acid active component was 4:1. C8H was weighed out. 20O4Si was slowly added dropwise to the mixed solution of rare earth La and Ce modified doped phosphotungstic acid active components prepared in step one. After stirring uniformly for 2 hours, the mixture was allowed to stand in the dark for 12 hours to obtain a dispersion solution of rare earth La and Ce modified doped phosphotungstic acid and SiO2. Using a pre-assembled 3D stainless steel metal fiber as a structural carrier, the stainless steel θ-ring packing was cut and wound into a θ-ring hollow structure, similar to the structure of stainless steel θ-ring packing used in distillation, to obtain 3D stainless steel metal fiber θ-ring packing. The 3D stainless steel metal fiber θ-ring packing was immersed in the dispersion solution of rare earth La and Ce modified doped phosphotungstic acid and SiO2 and ultrasonically vibrated for 1 hour. Then, it was dried in a drying oven at 100°C for 2 hours. The coating and drying operation was repeated 6 times. Finally, it was heated to 400°C in a muffle furnace and heated continuously for 6 hours to obtain the rare earth doped phosphotungstic acid structural catalyst (La-Ce-Ag-PW-SiO2 / SS-fibe).

[0083] Example 11

[0084] This embodiment proposes an application of a rare earth Ce-doped phosphotungstic acid structure catalyst. The rare earth-doped phosphotungstic acid structure catalyst prepared by the above-mentioned method is used to catalyze esterification to prepare biodiesel or to remove thiophene compounds from diesel fuel through oxidative desulfurization.

[0085] To verify the effectiveness of this invention, its performance in catalytic esterification for biodiesel production and oxidative desulfurization was evaluated:

[0086] Performance evaluation of biodiesel preparation by catalytic esterification using catalysts prepared in Examples 3, 6, and 9:

[0087] According to a methanol-oleic acid molar ratio of 6:1, 19.2g of methanol and 28.2g of oleic acid were weighed and added to a three-necked flask. Then, based on 4% of the oleic acid mass, the required rare earth-doped phosphotungstic acid catalyst was weighed. The reaction was carried out under stirring at a heating temperature of 55℃. Every hour, 0.2-0.5g of sample was taken, and 50ml of boiling anhydrous ethanol was added to the sample. Phenolphthalein was added dropwise as an acid-base indicator. After mixing thoroughly, the acid value was calculated by titration with 0.1mol / L potassium hydroxide solution.

[0088] Acid value is calculated using the following formula:

[0089] S=56.1×ΔV×C / m

[0090] In the formula, ΔV is the volume of potassium hydroxide consumed before and after titration; m is the mass of the sample to be tested; 56.1 is the molecular weight of potassium hydroxide; and C is the concentration of potassium hydroxide.

[0091] The oleic acid conversion rate is calculated using the following formula:

[0092] Conversion rate = (1 - acid value after reaction / acid value before reaction) × 100%

[0093] The desulfurization performance of the catalysts prepared in Examples 3, 6, and 9 was evaluated.

[0094] Weigh 0.15g of thiophene and 29.26g of n-octane to prepare a simulated oil with a sulfur content of 2000ppm. Add 3.03g of 30% hydrogen peroxide according to the oxygen-sulfur ratio (O / S) of thiophene and H2O2 = 30. Add a rare earth-doped phosphotungstic acid structured catalyst at 2% of the total mass of the thiophene simulated oil, mix well, and add to a three-necked flask. Heat to 60℃ and stir. Every 0.5h, take 1-2ml of the supernatant reaction liquid from the three-necked flask and detect the sulfur content by gas chromatography.

[0095] The desulfurization rate is calculated using the following formula:

[0096] X=(C0-C t ) / C0×100%

[0097] In the formula, X is the desulfurization rate; C0 is the thiophene concentration before the reaction; C t This represents the residual concentration of thiophene after the reaction.

[0098] from Figure 1 It can be seen that the rare earth-doped phosphotungstic acid structure catalyst is effectively loaded on the surface of stainless steel fiber. With stainless steel fiber as the supporting framework and rare earth La and Ce-doped phosphotungstic acid active components as the shell layer, the microreactor structure design improves the stability of the catalyst.

[0099] from Figure 2 It can be seen that the characteristic peaks of the rare earth La and Ce doped phosphotungstic acid active components match those of the phosphotungstic acid sample. The characteristic peaks of La-Ce-Ag-PW are slightly shifted towards a small angle. This is because the metal ions used to modify phosphotungstic acid exchange hydrogen protons with phosphotungstic acid, which shortens the axis length in the HPW lattice. This indicates that the doped metal ions effectively modify phosphotungstic acid. The characteristic peaks of the structural catalyst sample include both the characteristic peaks of stainless steel fibers and some characteristic peaks of rare earth La and Ce doped phosphotungstic acid active components, indicating that the active components are uniformly dispersed and well loaded on the stainless steel fiber support.

[0100] from Figure 3It can be seen that the rare earth-doped phosphotungstic acid structure catalysts prepared in Examples 3, 6 and 9 exhibit a desorption peak corresponding to a weak acid site at 100-200℃, while Ce-Ag-PW and La-Ag-PW also exhibit a desorption peak corresponding to a medium-strength acid site at 250-350℃. The desorption peaks of both the weak acid site and the medium-strength acid site in La-Ce-Ag-PW shift towards the increasing temperature direction. Based on the peak area comparison, the addition of La increases the acid strength of the catalyst and reduces the acid content.

[0101] from Figure 4 It can be seen that the rare earth-doped phosphotungstic acid structure catalysts prepared in Examples 3, 6 and 9 have better acid catalytic activity than the unmodified phosphotungstic acid structure catalyst (HPW-SiO2 / SS-fibe). The doping of rare earth elements La and Ce significantly improves the reaction conversion rate of oleic acid. The improvement effect of doping with two rare earth elements is better than that of doping with a single rare earth element.

[0102] from Figure 5 It can be seen that the rare earth-doped phosphotungstic acid structure catalysts prepared in Examples 3, 6 and 9 have better oxidation activity than the unmodified phosphotungstic acid structure catalysts. The doping of rare earth elements La and Ce significantly improves the removal rate of thiophene sulfur components. The doping of two rare earth elements makes the catalyst's oxidation performance better than that of a single rare earth element.

[0103] from Figure 6 It can be seen that rare earth-doped phosphotungstic acid structured catalysts, after structural reactor design, can be effectively applied to reactive distillation, a chemical process intensification technology. By optimizing and controlling process parameters such as reboiler heating temperature, weight hourly space velocity, reflux ratio, and feed propionic acid / methanol molar ratio, efficient esterification reaction of propionic acid and methanol can be achieved while effectively separating the product methyl propionate from the feed.

[0104] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. Use of a rare earth and silver doped phosphotungstic acid structure catalyst, characterized in that, The rare earth and silver doped phosphotungstic acid structure catalyst is used for removing thiophene compounds in diesel oil by oxidative desulfurization conversion, and the method for preparing the rare earth and silver doped phosphotungstic acid structure catalyst comprises the following steps: Phosphotungstic acid powder is weighed and added into first deionized water to prepare a phosphotungstic acid solution by stirring at room temperature; La(NO3)3·6H2O and / or Ce(NO3)3·6H2O are weighed, and then AgNO3 is weighed, and the weighed La(NO3)3·6H2O and / or Ce(NO3)3·6H2O and AgNO3 are added into second deionized water to prepare a metal salt solution by stirring at room temperature; The metal salt solution is slowly added into the phosphotungstic acid solution to obtain a metal modified phosphotungstic acid mixed solution, and the metal modified phosphotungstic acid mixed solution is stirred at room temperature to obtain a rare earth and silver modified doped phosphotungstic acid active component mixed solution; C8H 20 O4Si was slowly added into the mixed solution of the active component of the rare earth and silver modified doped phosphotungstic acid, and after uniform stirring, the dispersion solution of the rare earth and silver modified doped phosphotungstic acid and SiO2 was obtained by avoiding light and standing. The 3D stainless steel metal fiber θ net ring packing is obtained by cutting and winding the whole 3D stainless steel metal fiber into a hollow θ ring structure similar to the stainless steel θ net ring packing used in rectification. The 3D stainless steel metal fiber θ net ring packing is immersed in a dispersion solution and treated by ultrasonic oscillation, and then dried; after several cycles of ultrasonic oscillation treatment and drying treatment, calcination is performed, and after the calcination is completed, a rare earth doped phosphotungstic acid structure catalyst is obtained.

2. The use of a rare earth and silver doped phosphotungstic acid structure catalyst according to claim 1, characterized in that, During the preparation of the phosphotungstic acid solution, the mass of the phosphotungstic acid is 1-3 g, and the preset volume of the first deionized water is 10-30 ml.

3. The use of a rare earth and silver doped phosphotungstic acid structure catalyst according to claim 2, characterized in that, During the preparation of the metal salt solution, when the weighed La(NO3)3·6H2O and AgNO3 are added into the second deionized water, the mass of the La(NO3)3·6H2O is 0.05-0.5 g, the mass of the AgNO3 is 0.1-0.5 g, and the preset volume of the second deionized water is 5-30 ml. When the weighed Ce(NO3)3·6H2O and AgNO3 are added into the second deionized water, the mass of the Ce(NO3)3·6H2O is 0.05-0.5 g, the mass of the AgNO3 is 0.1-0.5 g, and the preset volume of the second deionized water is 5-30 ml. When the weighed La(NO3)3·6H2O and Ce(NO3)3·6H2O and AgNO3 are added into the second deionized water, the mass of the AgNO3 is 0.1-0.5 g, the mass of the Ce(NO3)3·6H2O is 0.05-0.5 g, the mass of the La(NO3)3·6H2O is 0.05-0.5 g, and the preset volume of the second deionized water is 5-30 ml.

4. The use of a rare earth and silver doped phosphotungstic acid structure catalyst according to claim 3, characterized in that, During the preparation of the rare earth and silver modified doped phosphotungstic acid active component mixed solution, the stirring time of the metal modified phosphotungstic acid mixed solution at room temperature is 0.5-1 h.

5. The use of a rare earth and silver doped phosphotungstic acid structure catalyst according to claim 4, characterized in that, In the preparation of rare earth and silver modified doped phosphotungstic acid and SiO2 dispersion solution process, C8H 20 The mass ratio of C8H4Si and metal modified phosphotungstic acid mixed solution is 0.5:1~4:1, the stirring time is 1~2h, and the light-free standing time is 5~12h.

6. The use of a rare earth and silver doped phosphotungstic acid structure catalyst according to claim 5, characterized in that, During the ultrasonic oscillation treatment and drying operation, the cycle number is 3-6 times, the ultrasonic oscillation treatment time is 0.1-1 h, the drying is performed by using a drying oven, the drying temperature is 100°C, and the drying time is 2 h.

7. The use of the rare earth and silver doped phosphotungstic acid structure catalyst according to claim 6, wherein the calcination is performed in a muffle furnace at a temperature of 200-400 °C for a time of 3-6 h.

Images