Chlorine modified carbon nanotube mercury adsorbent and preparation method and regeneration method thereof
By using chlorine-modified carbon nanotubes as mercury adsorption agents, the wet desorption method is used to achieve efficient adsorption and regeneration of mercury, which solves the problems of high adsorption and regeneration costs and high energy consumption in the prior art, and achieves an efficient and environmentally friendly mercury treatment effect.
Patent Information
- Application Number
- CN202411936875.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-03-18
AI Technical Summary
The prior art is difficult to efficiently and at low cost to adsorb trace amounts of mercury in coal gas, and traditional thermal desorption methods are prone to damage adsorbents and have high energy consumption.
Chlorine-modified carbon nanotubes are used as mercury adsorbents to produce two active sites, copper and chlorine, by reacting with copper chloride solution, achieving efficient adsorption of mercury in coal gas. The wet desorption method is used to transfer mercury in the form of Hg2+ to the eluent, and the regeneration of the adsorbent is achieved through the repair of the active site.
It achieves efficient, low-cost and environmentally friendly mercury adsorption and regeneration, avoids the problem of high-temperature damage to adsorbents, reduces energy consumption, and provides a sustainable green regeneration method.
Smart Images
Figure CN119633752A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of environmental pollution control, and in particular relates to a chlorine-modified carbon nanotube mercury adsorbent and a preparation method and a regeneration method thereof. Background Art
[0002] Heavy metal mercury (Hg) is a typical unconventional air pollutant that has caused serious harm to the ecological environment and human health. Coal combustion accounts for about 40% of man-made mercury emissions. At the same time, coal gasification technology is considered to have great potential due to its high efficiency and cleanliness. Therefore, the adsorbent for trace mercury in coal gas is the top priority in the research and development of mercury adsorbents. In coal gas, the escape forms of mercury can be divided into three types: elemental mercury (Hg 0 ), oxidized mercury (Hg 2+ ) and particulate mercury (Hg p ), among which elemental mercury is highly toxic, chemically inert, and bioaccumulative, making it difficult to remove using particulate matter capture devices, and is the key to the development of mercury adsorbents.
[0003] Adsorption capture dry mercury removal technology is the most mature tail gas mercury removal technology currently used. By installing solid adsorbents upstream of the flue, Hg 0 It is converted into adsorbed mercury on the mercury adsorbent, and most of the mercury elements in the coal gas are removed by recollecting the mercury adsorbent. But in fact, due to the short gas-solid contact time between the adsorbent and the coal gas, a large amount of mercury adsorbent is required in most application scenarios, which greatly increases the cost of the mercury adsorbent. In order to actively respond to the sustainable development strategy, it is of great value to develop renewable mercury adsorbents, create a recyclable mercury adsorbent system, and realize the regeneration and reuse of mercury adsorbents.
[0004] At present, waste mercury adsorbents are usually landfilled. However, the landfill method only buries the adsorbent in the soil, and the divalent mercury in it will still be separated from the adsorbent and enter the environment due to environmental influences. In addition, the more commonly used method is thermal desorption, which is based on the principle of heating the mercury adsorbent to a high temperature to decompose the mercury compounds on the adsorbent to generate Hg 0 And collect. However, high temperature can easily cause irreversible damage to the adsorbent, and the heating container and energy consumption generated in the process are difficulties that need to be solved urgently. Wet desorption removes mercury compounds on the mercury adsorbent through solution, directly recovers mercury and does not damage the active sites on the adsorbent, which has good prospects.
[0005] Therefore, it is of great significance to develop a new chlorine-modified carbon nanotube mercury adsorbent and study its preparation method and regeneration method. Summary of the invention
[0006] The technical problem to be solved by the present invention is to provide an adsorbent that can efficiently and massively adsorb mercury in coal gas and remove mercury and regenerate it through wet desorption. The specific implementation principle of wet desorption and adsorbent regeneration is to design the active sites of the adsorbent and the solute of the eluent, and to convert mercury into Hg 2+ The adsorbent is transferred to the eluent in a form and the repair of the relevant active sites and the regeneration of the adsorbent are completed. The adsorbent and the corresponding wet desorption can achieve the advantages of high efficiency, low cost, environmental friendliness, and reusability, which is conducive to use in engineering.
[0007] In order to solve the above technical problems, the present invention discloses a chlorine-modified carbon nanotube mercury adsorbent, wherein the mercury adsorbent uses carbon nanotubes as substrates and copper chloride as a modifier; the copper chloride simultaneously generates two active sites of copper and chlorine on the surface of the carbon nanotubes.
[0008] The present invention also provides a method for preparing the chlorine-modified carbon nanotube mercury adsorbent, which specifically comprises the following steps: mixing and stirring the carbon nanotubes and a copper chloride solution and heating them together, and then performing solid-liquid separation, drying and grinding to obtain the mercury adsorbent.
[0009] Specifically, the solid-liquid ratio of the carbon nanotubes and the copper chloride solution is 100 mg: (20-50) ml; preferably, the solid-liquid ratio is 100 mg: 20 ml.
[0010] Specifically, the concentration of the cupric chloride solution is 0.05-0.8 mol / L, and the solvent is deionized water; preferably, the concentration of the cupric chloride solution is 0.4-0.6 mol / L.
[0011] Specifically, the stirring is performed at a speed of 400 to 600 r / min for 25 to 55 min; the co-heating is performed at a temperature of 50 to 70° C.;
[0012] Preferably, the stirring is carried out at a speed of 500 r / min and a time of 45 min; and the co-heating is carried out at a temperature of 60° C.
[0013] Specifically, the solid-liquid separation is performed by vacuum filtration.
[0014] Specifically, the drying temperature is 50-70° C. and the time is 12 hours.
[0015] Specifically, in some embodiments of the present invention, by performing XPS analysis on the chlorine-modified carbon nanotube mercury adsorbent prepared by the above method and testing the adsorption rate of mercury by the mercury adsorbent under different atmospheres, it is shown that there is Cl in the XPS fitting curve of the chlorine-modified carbon nanotube mercury adsorbent. -The characteristic peaks of C-Cl and C-Cl indicate that the reaction between copper chloride and carbon nanotubes will generate a large number of active sites for chlorine. The test of the adsorption rate of mercury shows that the mercury adsorbent provided by the present invention has an adsorption efficiency of more than 90%, proving the application prospect of the chlorine-modified carbon nanotube mercury adsorbent provided by the present invention in the field of removing mercury from fixed source tail gas.
[0016] Preferably, the fixed source tail gas includes one of coal-fired flue gas, synthesis gas and non-ferrous metal smelting flue gas, and the operating temperature window is <100°C.
[0017] The present invention also provides a wet desorption regeneration method for the mercury adsorbent after the mercury adsorption, which specifically comprises the following steps: mixing the mercury-loaded chlorine-modified carbon nanotube mercury adsorbent with an eluent for reaction, and then performing solid-liquid separation and drying to complete the regeneration of the chlorine-modified carbon nanotube mercury adsorbent;
[0018] Wherein, the eluent is one of deionized water, hydrochloric acid solution or cupric chloride solution; preferably, the eluent is hydrochloric acid solution or cupric chloride solution;
[0019] Specifically, the concentrations of the hydrochloric acid solution and the copper chloride solution are 0.05 to 2 mol / L;
[0020] Preferably, the concentrations of the hydrochloric acid solution and the cupric chloride solution are 0.05 to 1 mol / L.
[0021] Specifically, the solid-liquid ratio of the mercury-loaded chlorine-modified carbon nanotube mercury adsorbent to the eluent is 40 mg:(20-50) mL; preferably, the solid-liquid ratio is 40 mg:30 mL.
[0022] Specifically, the reaction conditions are as follows: temperature of 30-50° C., stirring duration of 30-50 min, and rotation speed of 300 r / min.
[0023] Specifically, the solid-liquid separation is vacuum filtration separation.
[0024] Specifically, the drying temperature is 50-80° C. and the drying time is 12 hours.
[0025] Specifically, the chlorine-modified carbon nanotube adsorbent after wet desorption and regeneration can still be used to capture gas-phase mercury in coal-fired flue gas, and the application temperature window is <100°C.
[0026] Beneficial effects:
[0027] (1) The present invention uses carbon nanotubes as substrates. Carbon nanotubes have better effective surface area and reaction activity, and can better react with copper chloride solution to generate more active sites, which is conducive to the complete adsorption of mercury in coal gas. At the same time, copper chloride is used as chlorine modification to simultaneously generate two active sites of copper and chlorine on the surface of carbon nanotubes. Both active sites can react with elemental mercury to adsorb mercury;
[0028] (2) The wet desorption method adopted by the present invention, through the design of active sites, makes mercury mostly adsorbed in the form of mercuric chloride, which is conducive to the subsequent recovery of mercury by wet desorption and is also conducive to the selection of eluent in wet desorption. Low-cost eluent can be used, and even deionized water can be used for elution;
[0029] (3) In the regeneration method provided by the present invention, both eluents contain chlorine element, which can coordinate with mercury to accelerate the removal of mercury, and can provide new mercury oxidation sites to regenerate the mercury adsorbent, thereby providing a sustainable green regeneration method for the regeneration of mercury adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.
[0031] Figure 1 This is an XPS analysis chart of chlorine element on the surface of the mercury adsorbent prepared in Examples 1 to 5;
[0032] Figure 2 This is a bar graph of the mercury adsorption rate of the mercury adsorbent prepared in Examples 1 to 5 under two atmospheres. DETAILED DESCRIPTION
[0033] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.
[0034] Embodiment 1:
[0035] Weigh 0.2g of copper chloride and place it in 30ml of deionized water to make a copper chloride solution. Add 150mg of ground carbon nanotubes and stir at 60°C at a speed of 500r / min for 45min. Vacuum filter the solution, collect the solid and dry it in an oven at 60°C for 12h to remove moisture. Finally, grind the dried sample to obtain mercury adsorbent CNT0.2.
[0036] Embodiment 2:
[0037] Weigh 0.5g of copper chloride and place it in 30ml of deionized water to prepare a copper chloride solution. Add 150mg of ground carbon nanotubes and stir at 60°C at a speed of 500r / min for 45min. Vacuum filter the solution, collect the solid and dry it in an oven at 60°C for 12h to remove moisture. Finally, grind the dried sample to obtain mercury adsorbent CNT0.5.
[0038] Embodiment 3:
[0039] Weigh 1.5g of copper chloride and place it in 30ml of deionized water to make a copper chloride solution. Add 150mg of ground carbon nanotubes and stir at 60°C at a speed of 500r / min for 45min. Vacuum filter the solution, collect the solid and dry it in an oven at 60°C for 12h to remove moisture. Finally, grind the dried sample to obtain mercury adsorbent CNT1.5.
[0040] Embodiment 4:
[0041] Weigh 2.0g of copper chloride and place it in 30ml of deionized water to make a copper chloride solution. Add 150mg of ground carbon nanotubes and stir at 60°C at a speed of 500r / min for 45min. Vacuum filter the solution, collect the solid and dry it in an oven at 60°C for 12h to remove moisture. Finally, grind the dried sample to obtain mercury adsorbent CNT2.
[0042] Embodiment 5:
[0043] Weigh 2.5g of copper chloride and place it in 30ml of deionized water to make a copper chloride solution. Add 150mg of ground carbon nanotubes and stir at 60°C at a speed of 500r / min for 45min. Vacuum filter the solution, collect the solid and dry it in an oven at 60°C for 12h to remove moisture. Finally, grind the dried sample to obtain mercury adsorbent CNT2.5.
[0044] The mercury adsorbents prepared in Examples 1 to 5 were characterized by X-ray photoelectron spectroscopy. Figure 1 From bottom to top are the XPS analysis diagrams of chlorine on the surface of the mercury adsorbents prepared in Examples 1 to 5. It can be seen that there is Cl in the XPS fitting curve. - The characteristic peaks of copper chloride and C-Cl indicate that the reaction between copper chloride and carbon nanotubes will generate a large number of active sites for chlorine.
[0045] In nitrogen atmosphere (400ml / min mercury N 2 , 800ml / min balance N 2 ) and nitrogen hydrogen sulfide mixed atmosphere (400ml / min mercury N 2 、48ml / min H2 S, 752mL / min balance N 2 ) was used to test the adsorption rate of mercury on the mercury adsorbents prepared in Examples 1 to 5. The specific steps were as follows: the total flow rate of the simulated coal gas was 1200 ml / min, the mercury concentration at the inlet of the fixed bed was 60 μg / m 3 The amount of mercury adsorbent used was 50 mg, the reaction temperature was set to 60 ° C, and the mercury concentration was tested at the outlet. Figure 2 The bar graphs are of the mercury adsorption rates of the mercury adsorbents prepared in Examples 1 to 5 under two atmospheres (the mercury adsorption rate is calculated by taking the difference between the inlet mercury concentration and the outlet mercury concentration and dividing it by the inlet mercury concentration). It can be seen from the graph that as the amount of copper chloride increases, the mercury adsorption rate of the chlorine-modified carbon nanotubes increases as a whole, and gradually tends to saturation and presents irregular changes after reaching 90%, indicating that the chlorine-modified carbon nanotubes have good adsorption properties under both atmospheres.
[0046] Embodiment 6:
[0047] Weigh 40 mg of mercury-loaded chlorine-modified carbon nanotubes, place them in 30 ml of 0.1 mol / L hydrochloric acid solution, and stir them at a constant temperature of 300 r / min at 40°C for 45 min. Vacuum filter the solution, collect the solids and dry them in an oven at 60°C for 12 h to remove moisture; finally, the residual mercury content in the solids is monitored by a programmed temperature desorption test, and the elution performance is measured by the elution efficiency (the ratio of the difference in mercury content of the waste adsorbent before and after elution to the mercury concentration of the waste adsorbent before elution). The elution efficiency of the sample is 78.3%. It can be seen that the hydrochloric acid solution can elute the mercury adsorbent efficiently.
[0048] Embodiment 7:
[0049] Weigh 40mg of mercury-loaded chlorine-modified carbon nanotubes, place them in 30ml of 0.05mol / L copper chloride solution, and stir them at a constant temperature of 300r / min at 40℃ for 45min. Vacuum filter the solution, collect the solid and dry it in an oven at 60℃ for 12h to remove moisture; finally, the residual mercury content in the solid is monitored by temperature-programmed desorption test, and the elution performance is measured by elution efficiency (the ratio of the difference in mercury content of the waste adsorbent before and after elution to the mercury concentration of the waste adsorbent before elution). The elution efficiency of the sample is 78.2%. It can be seen that the copper chloride solution can elute the mercury adsorbent efficiently.
[0050] Embodiment 8:
[0051] Weigh 40 mg of mercury-loaded chlorine-modified carbon nanotubes, place them in 30 ml of deionized water, and stir them at a constant temperature of 300 r / min at 40°C for 45 min. The solution was vacuum filtered, the solid was collected and dried in an oven at 60°C for 12 h to remove moisture; finally, the residual mercury content in the solid was monitored by a programmed temperature desorption test, and the elution performance was measured by the elution efficiency (the ratio of the difference in mercury content of the waste adsorbent before and after elution to the mercury concentration of the waste adsorbent before elution). The elution efficiency of the sample was 61.2%. It can be seen that deionized water can elute the mercury adsorbent efficiently.
[0052] The present invention provides a chlorine-modified carbon nanotube mercury adsorbent and a preparation method and a regeneration method thereof. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.
Claims
1. A chlorine-modified carbon nanotube mercury adsorbent, characterized in that: The mercury adsorbent uses carbon nanotubes as substrates and copper chloride as a modifier; the copper chloride simultaneously generates two active sites of copper and chlorine on the surface of the carbon nanotubes.
2. The method for preparing the chlorine-modified carbon nanotube mercury adsorbent according to claim 1, characterized in that: The specific steps are: mixing, stirring and co-heating the carbon nanotubes and the copper chloride solution, and then performing solid-liquid separation, drying and grinding to obtain the mercury adsorbent.
3. The preparation method according to claim 2, characterized in that: The solid-liquid ratio of the carbon nanotubes and the copper chloride solution is 100 mg: (20-50) ml.
4. The preparation method according to claim 2 or 3, characterized in that: The concentration of the cupric chloride solution is 0.05-0.8 mol / L, and the solvent is deionized water.
5. The preparation method according to claim 2, characterized in that: The stirring is performed at a speed of 400 to 600 r / min for 25 to 55 min. The co-heating is performed at a temperature of 50 to 70°C.
6. Use of the chlorine-modified carbon nanotube mercury adsorbent according to claim 1 in the field of removing mercury from tail gas from fixed sources.
7. The method for regenerating the chlorine-modified carbon nanotube mercury adsorbent according to claim 1, characterized in that: The specific steps are: mixing the mercury-loaded chlorine-modified carbon nanotube mercury adsorbent with an eluent for reaction, and then performing solid-liquid separation and drying to complete the regeneration of the chlorine-modified carbon nanotube mercury adsorbent; Wherein, the eluent is one of deionized water, hydrochloric acid solution or cupric chloride solution.
8. The regeneration method according to claim 7, characterized in that: The concentrations of the hydrochloric acid solution and the cupric chloride solution are 0.05-2 mol / L.
9. The regeneration method according to claim 7, characterized in that: The solid-to-liquid ratio of the mercury-loaded chlorine-modified carbon nanotube mercury adsorbent to the eluent is 40 mg: (20-50) mL.
10. The regeneration method according to claim 7, characterized in that: The specific conditions of the reaction are: temperature of 30-50°C, stirring duration of 30-50min, and rotation speed of 300r / min.