Iron oxide/layered double-metal hydroxide compound and preparation and application thereof
阅读说明：本技术 一种氧化铁/层状双金属氢氧化物复合物及其制备、应用 (Iron oxide/layered double-metal hydroxide compound and preparation and application thereof ) 是由 崔洪珊 何杰 胡丽芳 朱继超 王俊峰 孙志鹏 徐李广 于 2019-11-11 设计创作，主要内容包括：本发明公开了一种氧化铁/层状双金属氢氧化物复合物,层状双金属氢氧化物上负载有氧化铁。本发明公开了上述氧化铁/层状双金属氢氧化物复合物的制备方法,包括如下步骤：将三价铁盐溶于水中,再加入层状双金属氢氧化物搅拌均匀,然后水热处理得到氧化铁/层状双金属氢氧化物复合物。本发明公开了上述氧化铁/层状双金属氢氧化物复合物在光催化脱硫领域中的应用。本发明通过在层状双金属氢氧化物中引入氧化铁,协同改善了光子的吸收和利用率,提高了光生载流子分离效率和表面催化反应效率,进而提高光催化活性,可应用于脱除有机硫。(The invention discloses an iron oxide/layered double hydroxide compound, wherein iron oxide is loaded on a layered double hydroxide. The invention discloses a preparation method of the ferric oxide/layered double hydroxide compound, which comprises the following steps: dissolving ferric salt in water, adding layered double hydroxide, stirring uniformly, and carrying out hydrothermal treatment to obtain the ferric oxide/layered double hydroxide compound. The invention discloses application of the ferric oxide/layered double hydroxide compound in the field of photocatalytic desulfurization. According to the invention, iron oxide is introduced into the layered double hydroxide, so that the absorption and utilization rate of photons are synergistically improved, the separation efficiency of photon-generated carriers and the surface catalytic reaction efficiency are improved, the photocatalytic activity is further improved, and the method can be applied to removal of organic sulfur.)
1. An iron oxide/layered double hydroxide composite characterized in that the layered double hydroxide is loaded with iron oxide.
2. The iron oxide/layered double hydroxide composite according to claim 1, wherein the iron oxide is supported between layers of the layered double hydroxide; preferably, the layered double hydroxide is a zinc-titanium based layered double hydroxide.
3. The iron oxide/layered double hydroxide composite according to claim 1 or 2, wherein the mass ratio of iron oxide to layered double hydroxide is 1 to 20: 100, respectively; preferably, the forbidden band width of the compound is 1.91-2.83 ev.
4. A method of preparing an iron oxide/layered double hydroxide composite according to any one of claims 1 to 3, comprising the steps of: dissolving ferric salt in water, adding layered double hydroxide, stirring uniformly, and carrying out hydrothermal treatment to obtain the ferric oxide/layered double hydroxide compound.
5. The method for preparing the iron oxide/layered double hydroxide composite according to claim 4, wherein the hydrothermal treatment comprises the following specific operations: 165 ℃ and 175 ℃ for aging for 15-17 h.
6. The method for preparing an iron oxide/layered double hydroxide composite according to claim 4 or 5, wherein the ferric salt is at least one of ferric chloride, ferric nitrate, ferric sulfate, ferric phosphate and ferric citrate, preferably ferric chloride.
7. The method for preparing an iron oxide/layered double hydroxide composite according to any one of claims 4 to 6, wherein when the layered double hydroxide is a zinc-titanium based layered double hydroxide, it is prepared by the following process: adding divalent zinc salt into alkaline solution, mixing, adding tetravalent titanium salt, stirring uniformly, and carrying out hydrothermal treatment to obtain the zinc-titanium-based layered double hydroxide.
8. The method for preparing an iron oxide/layered double hydroxide composite according to claim 7, wherein the hydrothermal treatment is carried out by: aging at 135 ℃ for 46-50h at 125 ℃.
9. The method for preparing an iron oxide/layered double hydroxide complex according to claim 7 or 8, wherein the divalent zinc salt is at least one of zinc chloride, zinc nitrate, zinc sulfate, zinc phosphate, zinc citrate, zinc lactate, zinc malate, and zinc acetate, preferably zinc nitrate; preferably, the tetravalent titanium salt is at least one of titanium chloride, titanium nitrate, titanium citrate and titanium acetate, and is preferably titanium chloride.
10. Use of an iron oxide/layered double hydroxide composite according to any one of claims 1 to 3 in the field of photocatalytic desulphurisation.
Technical Field
The invention relates to the technical field of photocatalysts, in particular to an iron oxide/layered double hydroxide compound and a preparation method and application thereof.
Background
With the rapid development of economy, the global fossil energy consumption is continuously increased, and the environmental pollution is increasingly serious. The conversion of sulfur compounds in petroleum products to SOX after combustion is one of the important causes of acid rain formation and air pollution. Thus, strict fuel sulfur standards are established throughout the world in various countries. Currently, china has promulgated the national gasoline standard at stage five. From 1 month and 1 day 2018, gasoline in the fifth stage is supplied nationwide, and the sulfur content of the Chinese gasoline is reduced to below 10 ppm. The production of low sulfur fuels has become one of the important tasks in modern refineries today.
In order to produce ultra low sulfur standard fuels, some early hydrodesulfurization processes must meet conditions of higher temperature, higher hydrogen pressure, higher catalyst activity, and longer reaction time. Deep desulfurization results in the production of certain secondary reactions, such as shortened catalyst life and increased hydrogen consumption, with severe yield losses and ultimately high costs.
The nano layered two-dimensional photocatalyst material mostly has larger specific surface area and more catalytic activity centers, which is beneficial to the catalytic reaction, and the method of laminate peeling and the like is used for reducing the layer number of the layered material, which is beneficial to the catalytic reaction, effectively reducing the bulk phase recombination rate of the photocarrier, and enabling the layered material to rapidly migrate to the surface for the catalytic reaction. The Layered Double Hydroxides (LDHs) have the advantages of adjustable chemical components of the laminate, easy exchange of anions between layers, multiple types of intercalation molecules, large specific surface area, topological transformation and the like, and can be used as ideal photocatalysts, catalyst carriers or precursors. Such as the use of the desulfurization reagent of the transition Wu Chang, Mengmeng Wu, Jie Mi. pyrolysis kinetics of ZnAl LDHs and its calcium products for H2S removal [ J ]. Journal of Thermal Analysis & calibration, 2018,132(1)581-589. the desulfurization reagent of Yu N L, Yang Z, Yu Z B, Cai T F, Li Y, Guo C Y, Qi C Y, Ren T Q. Synthesis of four-angle stage-like CoAl-
However, catalytic activity of the LDHs photocatalytic material is still low, which limits the application of the LDHs photocatalytic material in the field of photocatalytic oxidation desulfurization.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides an iron oxide/layered double hydroxide compound and a preparation method and application thereof.
An iron oxide/layered double hydroxide composite having iron oxide supported on a layered double hydroxide.
Preferably, the iron oxide is supported between the layers of the layered double hydroxide.
Preferably, the layered double hydroxide is a zinc-titanium based layered double hydroxide.
Preferably, the mass ratio of iron oxide to layered double hydroxide is 1-20: 100, respectively; may be 1: 100. 1.2: 100. 2: 100. 2.6: 100. 3: 100. 3.8: 100. 4: 100. 4.7: 100. 5: 100. 5.6: 100. 6: 100. 6.1: 100. 7: 100. 7.7: 100. 8: 100. 8.3: 100. 9: 100. 9.6: 100. 10: 100. 10.5: 100. 11: 100. 12: 100. 13: 100. 14: 100. 15: 100. 16: 100. 17: 100. 18: 100. 18.5: 100. 19: 100. 19.2: 100. 20: 100.
preferably, the forbidden band width of the compound is 1.91-2.83 ev.
Since iron oxide is a semiconductor photocatalyst having a very wide prospect, its photocatalytic activity is constantly and rapidly improved, and it has the following advantages as a photocatalyst:
1. iron oxide is an important N-type semiconductor, has the forbidden band width of about 2.1eV, can absorb and utilize light with the wavelength of below 600nm, and is a visible light photocatalyst with excellent performance;
2. the iron oxide is rich in the earth crust, has low price and is suitable for large-scale production and utilization;
3. the ferric oxide has good stability in aqueous solution, especially in alkaline solution, and is suitable for practical application.
The invention introduces object-ferric oxide into the layered double hydroxide for compounding, synergistically improves the absorption and utilization rate of photons, improves the separation efficiency of photon-generated carriers and the surface catalytic reaction efficiency, further improves the photocatalytic activity of the composite material, and can be applied to the removal of organic sulfur.
The preparation method of the iron oxide/layered double hydroxide compound comprises the following steps: dissolving ferric salt in water, adding layered double hydroxide, stirring uniformly, and carrying out hydrothermal treatment to obtain the ferric oxide/layered double hydroxide compound.
Preferably, the hydrothermal treatment is carried out by the following specific operations: 165 ℃ and 175 ℃ for aging for 15-17 h. The temperature can be 165 deg.C, 165.1 deg.C, 166 deg.C, 166.3 deg.C, 167 deg.C, 167.4 deg.C, 168 deg.C, 168.5 deg.C, 169 deg.C, 169.8 deg.C, 170 deg.C, 170.5 deg.C, 171 deg.C, 171.4 deg.C, 172 deg.C, 172.5 deg.C, 173 deg.C, 173.8 deg.C, 174 deg.C; the aging time can be 15h, 15.2h, 15.4h, 15.6h, 15.8h, 16h, 16.1h, 16.3h, 16.5h, 16.7h, 16.9h and 17 h.
Preferably, after hydrothermal treatment, the mixture is filtered by suction, the filter cake is washed to be neutral, and the mixture is dried in vacuum.
Preferably, the washing is carried out with an aqueous ethanol solution.
Preferably, the vacuum drying temperature is 65-75 ℃, and the vacuum drying time is 20-28 h. The temperature can be 65 deg.C, 65.2 deg.C, 66 deg.C, 66.4 deg.C, 67 deg.C, 67.6 deg.C, 68 deg.C, 68.8 deg.C, 69 deg.C, 69.5 deg.C, 70 deg.C, 70.1 deg.C, 71 deg.C, 71.3 deg.C, 72 deg.C, 72.5 deg.C, 73 deg.C, 73.7 deg.C, 74 deg.C; the time can be 20h, 20.1h, 21h, 21.3h, 22h, 22.5h, 23h, 23.7h, 24h, 24.9h, 25h, 25.2h, 26h, 26.4h, 27h, 27.6h and 28 h.
Preferably, the ferric salt is at least one of ferric chloride, ferric nitrate, ferric sulfate, ferric phosphate and ferric citrate, and is preferably ferric chloride.
Preferably, when the layered double hydroxide is zinc-titanium based layered double hydroxide, it is prepared by the following process: adding divalent zinc salt into alkaline solution, mixing, adding tetravalent titanium salt, stirring uniformly, and carrying out hydrothermal treatment to obtain the zinc-titanium-based layered double hydroxide.
Preferably, the alkaline solution is an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous calcium hydroxide solution, an aqueous diethylamine solution, an aqueous triethylamine solution, an aqueous diethanolamine solution, an aqueous triethanolamine solution, an aqueous urea solution, preferably an aqueous urea solution, more preferably an aqueous urea solution having a concentration of 20 to 30mol/L, and the concentration thereof may be 20mol/L, 21mol/L, 22mol/L, 23mol/L, 24mol/L, 25mol/L, 26mol/L, 27mol/L, 28mol/L, 29mol/L, 30 mol/L.
Preferably, the molar ratio of the zinc ions to the titanium ions is 3: 1; this molar ratio can be increased or decreased depending on the structure of the product-Zn-Ti based layered double hydroxide, but only affects the yield of the product and does not affect the formation of the product, so that a molar ratio inconsistent with this range is still considered to fall within the scope of protection.
Preferably, the hydrothermal treatment is carried out by the following specific operations: aging at 135 ℃ for 46-50h at 125 ℃. The temperature can be 125 deg.C, 125.2 deg.C, 126 deg.C, 126.4 deg.C, 127 deg.C, 127.6 deg.C, 128 deg.C, 128.8 deg.C, 129 deg.C, 130 deg.C, 130.1 deg.C, 131 deg.C, 131.3 deg.C, 132 deg.C, 132.5 deg.C, 133 deg.C, 133.7 deg.C, 134 deg.C, 134.9 deg.C, 135 deg.C, and the aging time can be 46h, 46.2h, 47h, 47.4h, 48h, 48.6 h.
Preferably, after hydrothermal treatment, the mixture is filtered by suction, the filter cake is washed to be neutral, and the mixture is dried in vacuum.
Preferably, the washing is carried out with absolute ethanol and an aqueous ethanol solution in this order.
Preferably, the ethanol aqueous solution is obtained by mixing absolute ethanol and deionized water according to an equal volume ratio.
Preferably, the vacuum drying temperature is 55-65 ℃, and the vacuum drying time is 10-14 h. The temperature can be 55 deg.C, 55.2 deg.C, 56 deg.C, 56.4 deg.C, 57 deg.C, 57.6 deg.C, 58 deg.C, 58.8 deg.C, 59 deg.C, 59.5 deg.C, 60 deg.C, 60.1 deg.C, 61 deg.C, 61.3 deg.C, 62 deg.C, 62.5 deg.C, 63 deg.C, 63.7 deg.C, 64.9 deg.C; the time can be 10h, 10.2h, 11h, 11.4h, 12h, 12.6h, 13h, 13.8h and 14 h.
Preferably, the divalent zinc salt is at least one of zinc chloride, zinc nitrate, zinc sulfate, zinc phosphate, zinc citrate, zinc lactate, zinc malate and zinc acetate, and is preferably zinc nitrate.
Preferably, the tetravalent titanium salt is at least one of titanium chloride, titanium nitrate, titanium citrate and titanium acetate, and is preferably titanium chloride.
The invention adopts a hydrothermal synthesis method to prepare the layered double hydroxide, and then obtains the ferric oxide/layered double hydroxide compound by a compound hybridization method, the preparation process is simple, the ferric oxide is effectively loaded between the layers of the layered double hydroxide, the forbidden bandwidth is reduced, the wavelength range of the absorbable light is expanded, the separation efficiency of the photon-generated carrier and the surface catalytic reaction efficiency are improved, and the separation efficiency of the photon-generated electron-hole pair is enhanced.
The ferric oxide/layered double hydroxide compound is applied to the field of photocatalytic desulfurization.
The LDHs have the advantages of easy adjustment of chemical composition of a coating, easy exchange of anions between layers, various types of embedded molecules, large specific surface area and topological transformation. However, the LDHs has low photocatalytic activity, which limits the application of the LDHs in the field of photocatalysis.
The invention constructs the metal semiconductor material composite LDHs photocatalytic material by introducing the object oxide particles-ferric oxide, and obtains the composite material with higher photocatalytic efficiency for removing the organic sulfide ethanethiol.
Drawings
FIG. 1 is a graph showing comparative X-ray diffraction patterns of the iron oxide/zinc-titanium based layered double hydroxide composites obtained in examples 3 to 6, the zinc-titanium based layered double hydroxide obtained in comparative example 1, and the iron oxide obtained in comparative example 2.
Fig. 2 is a graph of the peak area integrals at 36 ° for each set of 2 θ in fig. 1.
Fig. 3 is an enlarged view of fig. 1.
FIG. 4 is an enlarged view of the main peak regions of each group in FIG. 3.
FIG. 5 is an electron micrograph of the iron oxide obtained in comparative example 2.
FIG. 6 is an electron microscope scan of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 3.
FIG. 7 is a UV-VIS absorption spectrum analysis spectrum of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in examples 3-6, the zinc-titanium based layered double hydroxide obtained in comparative example 1, and the iron oxide obtained in comparative example 2.
FIG. 8 is a graph showing the distribution of the forbidden band widths of the zinc-titanium based layered double hydroxide obtained in comparative example 1 and the iron oxide obtained in comparative example 2.
FIG. 9 is a distribution diagram of the forbidden bandwidth of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 3.
FIG. 10 is a distribution diagram of the forbidden bandwidth of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 4.
FIG. 11 is a distribution diagram of the forbidden bandwidth of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 5.
FIG. 12 is a distribution diagram of the forbidden bandwidth of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 6.
FIG. 13 is an electrochemical impedance spectrum of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in examples 3 to 7, the zinc-titanium based layered double hydroxide obtained in comparative example 1, and the iron oxide obtained in comparative example 2.
FIG. 14 is a graph showing transient photocurrent responses of the iron oxide/zinc-titanium based layered double hydroxide composites obtained in examples 3 to 7, the zinc-titanium based layered double hydroxide obtained in comparative example 1, and the iron oxide obtained in comparative example 2 under visible light irradiation.
FIG. 15 is a Mott-Schottky graph of the zinc-titanium based layered double hydroxide obtained in comparative example 1.
FIG. 16 is a Mott-Schottky graph of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 3.
FIG. 17 is a Mott-Schottky graph of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 4.
FIG. 18 is a Mott-Schottky graph of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 5.
FIG. 19 is a Mott-Schottky graph of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 6.
FIG. 20 is a Mott-Schottky plot of the iron oxide obtained in comparative example 2.
FIG. 21 is a FT-IR spectrum of iron oxide adsorbing degraded ethanethiol obtained in comparative example 2.
FIG. 22 is a FT-IR spectrum of the zinc-titanium based layered double hydroxide obtained in comparative example 1 with adsorption of degraded ethanethiol.
FIG. 23 is a FT-IR spectrum of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 3 adsorbing and degrading ethanethiol.
FIG. 24 is a FT-IR spectrum of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 4 adsorbing and degrading ethanethiol.
FIG. 25 is a FT-IR spectrum of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 5 adsorbing and degrading ethanethiol.
FIG. 26 is a FT-IR spectrum of the iron oxide/zinc-titanium based layered double hydroxide composite obtained in example 6 adsorbing and degrading ethanethiol.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to specific examples.
The main experimental instruments used were as follows:
the main reagents used were as follows:
the ethanol aqueous solution used for the following washing is obtained by mixing absolute ethyl alcohol and deionized water according to an equal volume ratio.