A method for simultaneously improving degradation of toluene activity and water resistance by using a catalyst prepared from resource recycling blast furnace slag

Abstract

This invention discloses a catalyst prepared from recycled blast furnace slag and a method for simultaneously improving the activity and water resistance of toluene degradation using it. The method includes: optimizing the recovery of titanium-based blast furnace slag with Mn and Ce co-doping to prepare a MnCe / CaTiO3 dual-site high-efficiency catalyst; applying the MnCe / CaTiO3 catalyst to degrade toluene, where Mn activates lattice oxygen to generate oxygen species, thus improving the activity for toluene degradation, and Ce decomposes water to generate hydroxyl species, thus improving the water resistance of toluene degradation, ultimately achieving simultaneous improvement in both the activity and water resistance of toluene degradation. This invention enables the efficient recycling of titanium-based blast furnace slag, promotes the degradation of toluene pollutants, solves environmental problems, and generates certain economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of waste residue resource utilization and volatile organic pollutant treatment, specifically involving a catalyst obtained from the resource recovery of blast furnace slag and a method for simultaneously improving the activity and water resistance of toluene degradation using it. Background Technology

[0002] Blast furnace slag, a byproduct of ironmaking, accounts for approximately 50% of the solid waste generated in the steel industry. Generally, smelting one ton of pig iron produces over 300 kilograms of blast furnace slag. The accumulation of large amounts of slag not only pollutes the environment but also represents a waste of resources. Currently, the main uses of slag are as roadbed material and in cement production, which are limited in scope and inefficient. The rich elemental composition, flexible structure, high stability, resistance to sintering, and resistance to carbon buildup of slag are seriously overlooked. There is an urgent need to develop a more advanced and efficient method for slag recycling, such as recycling slag for use as a catalyst or carrier for pollutant degradation, thereby creating greater economic value.

[0003] Toluene, a typical volatile organic pollutant, harms the human respiratory and central nervous systems, directly pollutes the air, and participates in photochemical reactions to generate secondary pollutants, making toluene disposal an urgent issue. Currently, toluene disposal methods mainly include physical adsorption, photocatalytic degradation, membrane separation, and chemical catalytic combustion. Among these, catalytic combustion, which directly oxidizes and degrades toluene into CO2 and H2O, has attracted considerable attention. However, this method is limited by the catalyst and often faces challenges such as low catalyst activity and susceptibility to water poisoning. Summary of the Invention

[0004] The main objective of this invention is to provide a toluene degradation catalyst and a method for preparing the toluene degradation catalyst by resource recovery of blast furnace slag.

[0005] The toluene degradation catalyst provided by this invention is prepared using titanium-based blast furnace slag as a carrier and Mn and Ce as doping elements.

[0006] The titanium-based blast furnace slag is a waste residue produced from titanium magnetite after ironmaking, and its main component is CaTiO3. The toluene degradation catalyst is designated as a MnCe / CaTiO3 dual-site high-efficiency catalyst. Based on the mass of the MnCe / CaTiO3 dual-site high-efficiency catalyst, the contents of Mn and Ce are both 5-10wt% (i.e., 100g of catalyst contains 5-10g of Mn and 5-10g of Ce), specifically, the Mn content is 10wt% and the Ce content is 5wt%.

[0007] This invention follows the Mars-van Krevelen (MvK) mechanism, using Mn metal elements to activate lattice oxygen and generate active oxygen species, thereby improving catalytic activity. Doping Ce elements decomposes H2O to generate hydroxyl active species, thereby improving water resistance. This invention is used to solve the problems of low catalyst activity and water poisoning in the inefficient utilization of blast furnace slag and the catalytic combustion of toluene in the prior art.

[0008] The toluene degradation catalyst was prepared by a method comprising the following steps: dispersing titanium-based blast furnace slag in water, adding manganese and cerium nitrates, stirring and impregnating, filtering to obtain a solid precipitate, drying, and calcining to obtain the catalyst; Wherein, the nitrate of Mn is a Mn(NO3)2 solution; The nitrate of cerium is Ce(NO3)3·5H2O; The mass ratio of the titanium-based blast furnace slag to manganese salt (calculated as Mn) and cerium salt (calculated as Ce) is 10g: 0.53-1.25g: 0.53-1.25g, respectively. The soaking time is 5-10 hours, specifically 8 hours; The drying is carried out in an air atmosphere; The drying temperature is 100-120°C, specifically 120°C; the drying time is 12-24 hours, specifically 24 hours. The roasting is carried out in an air atmosphere; The roasting temperature is 500-700°C, specifically 500°C; the roasting time is 6-12 hours, specifically 6 hours. The above method further includes the operation of pressing and sieving the roasted product to obtain 60-80 mesh particles.

[0009] The application of the above-mentioned toluene degradation catalyst in the degradation of toluene pollutants also falls within the scope of protection of this invention.

[0010] In the application described, the toluene degradation catalyst simultaneously improves both its toluene degradation activity and water resistance.

[0011] Using MnCe / CaTiO3 to degrade toluene, Mn is responsible for activating lattice oxygen to generate oxygen species, thereby improving the activity of toluene degradation, while Ce is responsible for decomposing water to generate hydroxyl species, thereby improving the water resistance of toluene degradation. Ultimately, this achieves a simultaneous improvement in both the activity of toluene degradation and water resistance.

[0012] The present invention also provides a method for degrading toluene.

[0013] The method for degrading toluene provided by the present invention includes the following steps: under the catalytic action of the toluene degradation catalyst, the toluene-containing gas undergoes a degradation reaction in the presence of water vapor.

[0014] The degradation reaction begins at a temperature of 100-200°C and ends at a temperature of 400-600°C; or the degradation reaction is carried out at a constant temperature of 300-500°C. The toluene-containing gas is a mixture of toluene, oxygen, and nitrogen. The flow rate of the toluene-containing gas is 25-100 mL / min (e.g., 60 mL / min). The water vapor is introduced into the reactor by a toluene-containing gas through a water container, and the humidity is 10%-75%.

[0015] The specific operation is as follows: the toluene degradation catalyst is placed in a tubular fluidized bed reactor, the air in the reactor is removed by purging with N2, the reactor temperature is raised to 100-200°C (specifically 100°C), the N2 is switched to a toluene mixture, the toluene mixture is carried by water vapor through an aqueous solution, and toluene is degraded under the action of the catalyst. The temperature is programmed to rise to 400-600°C (specifically 400°C) and the reaction ends. The composition of the toluene mixture is: 300-1000 ppm toluene, 10-21% oxygen, and nitrogen balance gas.

[0016] The beneficial effects of this invention are as follows: (1) Recycle and utilize titanium-based blast furnace slag, improve its utilization method and increase its utilization rate, and obtain greater economic and environmental benefits.

[0017] (2) Mn and Ce co-doping optimized modified slag, Mn is responsible for improving degradation activity, and Ce is responsible for improving the water resistance of toluene degradation. The two are used in synergy to simultaneously improve the activity and water resistance of toluene degradation.

[0018] (3) Use waste residue to degrade toluene pollutants, opening up a new model of "treating pollution with waste", solving environmental problems while creating greater economic value. Attached Figure Description

[0019] Figure 1 This is an aberration-corrected transmission electron microscope image of MnCe / CaTiO3 prepared in Example 1 of this invention.

[0020] Figure 2 X-ray photoelectron spectra of MnCe / CaTiO3 prepared in Example 1, Mn / CaTiO3 prepared in Comparative Example 1, and Ce / CaTiO3 prepared in Comparative Example 2.

[0021] Figure 3The H2O-programmed temperature desorption spectra of MnCe / CaTiO3 prepared in Example 1, Mn / CaTiO3 prepared in Comparative Example 1, and Ce / CaTiO3 prepared in Comparative Example 2 are shown.

[0022] Figure 4 Electron paramagnetic spectra of MnCe / CaTiO3 prepared in Example 1, Mn / CaTiO3 prepared in Comparative Example 1, and Ce / CaTiO3 prepared in Comparative Example 2 are shown.

[0023] Figure 5 The activity of MnCe / CaTiO3 in degrading toluene in Example 2 of the present invention is shown in a. a and b show the toluene conversion rate and CO2 generation rate, respectively.

[0024] Figure 6 To illustrate the water resistance of toluene degradation by MnCe / CaTiO3 in Example 3 of this invention, a and b show the toluene conversion rate and CO2 generation rate. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0027] Example 1: Preparation of MnCe / CaTiO3 catalyst Optimize and modify titanium-based blast furnace slag, co-dope with Mn and Ce, to prepare MnCe / CaTiO3.

[0028] 10 g of titanium-based blast furnace slag (mainly CaTiO3) was dispersed in 100 mL of ultrapure water. A certain amount of Mn(NO3)2 aqueous solution (containing 1.25 g of Mn) and Ce(NO3)3·5H2O solid (containing 0.53 g of Ce) were added, and the mixture was stirred continuously for 8 hours. The solid precipitate was obtained by filtration, washed three times with ultrapure water, and dried at 120°C for 24 hours. The solid was calcined in air at 500°C for 6 hours. The solid was compressed into tablets and sieved to obtain 60-80 mesh particles, ultimately yielding MnCe / CaTiO3.

[0029] Based on the mass of the catalyst (0.1g), in which the content of Mn is 10wt%, the content of Ce is 5wt%, and the balance is slag.

[0030] Figure 1 This is an aberration-corrected transmission electron microscope (TEM) image of the prepared MnCe / CaTiO3. The image clearly shows that Mn substitutes for some Ti sites and is incorporated into the slag, while Ce is incorporated into the slag as CeO2.

[0031] Example 2 The MnCe / CaTiO3 prepared in Example 1 was used to improve the activity of degrading toluene.

[0032] 0.1 g of MnCe / CaTiO3 was placed in a self-made tubular fluidized bed reactor. The air in the reactor was removed by purging with N2. The reactor temperature was raised to 100°C. The N2 was then switched to a toluene mixture. The toluene mixture (300 ppm toluene, 21% oxygen, and nitrogen balance gas) was loaded with water vapor through 5 mL of aqueous solution at a flow rate of 60 mL / min. The reactor humidity was 74.4%. The degradation of toluene began, and the temperature was programmed to rise to 400°C before the process ended.

[0033] Figure 5 The activity of MnCe / CaTiO3 in degrading toluene in Example 2. Figure 5 Figures a and b show the toluene conversion rate and CO2 generation rate. Compared with slag CaTiO3, Mn and Ce co-doping significantly improves the activity in degrading toluene.

[0034] Example 3 The MnCe / CaTiO3 obtained in Example 1 was used to improve the water resistance of degraded toluene.

[0035] 0.1 g of MnCe / CaTiO3 was placed in a self-made tubular fluidized bed reactor. The air in the reactor was removed by purging with N2. The reactor temperature was raised to 375°C (a constant temperature reaction at 375°C). The N2 was then switched to a toluene mixture (300 ppm toluene, 21% oxygen, and nitrogen balance gas). The flow rate was 60 mL / min. At this point, the reactor humidity was 27%. The water resistance of the degraded toluene was tested. The reaction was completed after 24 hours.

[0036] Figure 6 To improve the water resistance of toluene by degrading MnCe / CaTiO3. Figure 6 Figures a and b show the toluene conversion rate and CO2 generation rate. Mn and Ce co-doping significantly improves the water resistance of degraded toluene.

[0037] Comparative Example 1: Preparation of Mn / CaTiO3: 10 g of titanium-based blast furnace slag (mainly CaTiO3) was dispersed in 100 mL of ultrapure water, and a certain amount of Mn(NO3)2 aqueous solution (containing 1.11 g of Mn) was added. The mixture was stirred continuously for 8 hours. The solid precipitate was obtained by filtration, washed three times with ultrapure water, and dried at 120°C for 24 hours. The solid was calcined in air at 500°C for 6 hours. The solid was then pressed into tablets and sieved to obtain 60-80 mesh particles, finally yielding Mn / CaTiO3.

[0038] Comparative Example 2: Preparation of Ce / CaTiO3: Titanium-based blast furnace slag (10g, mainly composed of CaTiO3) was dispersed in 100mL of ultrapure water, and a certain amount of Ce(NO3)3·5H2O solid (containing 0.53g Ce) was added. The mixture was stirred continuously for 8 hours. The solid precipitate was obtained by filtration, washed three times with ultrapure water, and dried at 120°C for 24 hours. The solid was calcined in air at 500°C for 6 hours. The solid was then compressed into tablets and sieved to obtain 60-80 mesh particles, ultimately yielding Ce / CaTiO3.

[0039] Figure 2 These are X-ray photoelectron spectra of the different materials prepared in Example 1 and Comparative Examples 1 and 2. The results show that Mn doping significantly increases the oxygen content in the slag lattice, which helps to activate lattice oxygen to generate oxygen species and thus improve the activity of degrading toluene.

[0040] Figure 3 These are the H2O-programmed desorption spectra of different materials prepared in Example 1, Comparative Examples 1 and 2. The results show that MnCe co-doping generates more HOH active sites due to the dissociation of adsorbed water, promoting the formation of hydroxyl groups.

[0041] Figure 4 These are the electron paramagnetic spectra of different materials prepared in Example 1, Comparative Examples 1 and 2. The results show that water is decomposed to produce hydroxyl groups when MnCe is co-doped.

[0042] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A toluene degradation catalyst, prepared using titanium-based blast furnace slag as a carrier and Mn and Ce as doping elements.

2. The catalyst according to claim 1, characterized in that, The titanium-based blast furnace slag is the waste residue produced after ironmaking from titanomagnetite; or... The main component of the titanium-based blast furnace slag is CaTiO3.

3. The catalyst according to claim 1, characterized in that, Based on the mass of the toluene degradation catalyst, the contents of Mn and Ce are both 5-10 wt%.

4. A method for preparing the catalyst according to any one of claims 1-3, comprising the following steps: dispersing titanium-based blast furnace slag in water, adding manganese and cerium nitrates, stirring and impregnating, filtering to obtain a solid precipitate, drying, and calcining to obtain the catalyst.

5. The method according to claim 4, characterized in that, The nitrate of Mn is a Mn(NO3)2 solution; The nitrate of cerium is Ce(NO3)3·5H2O; The mass ratio of the titanium-based blast furnace slag to manganese salt (calculated as Mn) and cerium salt (calculated as Ce) is 10g: 0.53-1.25g: 0.53-1.25g, respectively. The soaking time is 5-10 hours; The drying is carried out in an air atmosphere; The drying temperature is 100-120°C; the drying time is 12-24 hours; The roasting is carried out in an air atmosphere; The roasting temperature is 500-700°C; the roasting time is 6-12 hours.

6. The use of the catalyst according to any one of claims 1-3 in the degradation of toluene contaminants.

7. The application according to claim 6, characterized in that, In the application described, the toluene degradation catalyst simultaneously improves both its toluene degradation activity and water resistance.

8. A method for degrading toluene, comprising the following steps: under the catalytic action of the toluene degradation catalyst according to any one of claims 1-3, causing the toluene-containing gas to undergo a degradation reaction in the presence of water vapor.

9. The method according to claim 8, characterized in that, The degradation reaction begins at a temperature of 100-200°C and ends at a temperature of 400-600°C. Alternatively, the degradation reaction may be carried out at a constant temperature of 300-500°C.

10. The method according to claim 8, characterized in that, The toluene-containing gas is a mixture of toluene, oxygen, and nitrogen. The flow rate of the toluene-containing gas is 25-100 mL / min; The water vapor is introduced into the reactor by a toluene-containing gas through a water container, and the humidity is 10%-75%.

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