CN-121972206-A - Modified iron monoatomic catalyst for pickling defect engineering and preparation method and application thereof

CN121972206ACN 121972206 ACN121972206 ACN 121972206ACN-121972206-A

Abstract

The invention belongs to the technical field of preparation of iron monoatomic catalysts, and particularly relates to an acid-washing defect engineering modified iron monoatomic catalyst, a preparation method and application thereof, wherein the surface of the acid-washing defect engineering modified iron monoatomic catalyst contains intrinsic defect sites, the content of Fe element is 0.60-0.67 wt%, the coordination form of Fe atoms is Fe-Nn, the coordination number N is 4.2+/-0.3, the bond length of Fe-N is 2.01A, and the valence state of Fe element is between Fe 2+ and Fe 3+ . According to the invention, through the synergistic strategy of the optimized proportioning design of the ZIF-8 precursor and the concentrated sulfuric acid pickling defect engineering, the controllable construction of defect sites and the remarkable improvement of catalytic activity are realized, the problems of difficult defect regulation and control and low utilization rate of active sites of the conventional Fe-N-C single-atom catalyst are solved, the technical bottlenecks of rapid activity attenuation and limited engineering application of the conventional catalyst in the recycling process are broken through, and the preparation process is simple, convenient, controllable, environment-friendly and has technical feasibility and economic rationality.

Inventors

LIU KE
GU JUNFEI
LAI BO
ZHANG YU
ZHENG YUNZHE
LI DAZHEN
LIU JIAMEI
Xiong Zhaogun
HE CHUANSHU

Assignees

四川大学

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (10)

1. The modified iron monoatomic catalyst for pickling defect engineering is characterized in that the surface contains intrinsic defect sites, the content of Fe element is 0.60-0.67wt%, the coordination form of Fe atoms is Fe-N n , the coordination number N is 4.2+/-0.3, the bond length of Fe-N is 2.01 a, and the valence state of Fe element is between Fe 2+ and Fe 3+ .
2. The method for preparing the pickling defect engineering modified iron monoatomic catalyst as claimed in claim 1, which is characterized by comprising the following steps: s1, mixing a zinc source, an iron source and 2-methylimidazole into methanol, wherein the molar ratio of Zn 2+ in the zinc source to Fe 3+ in the iron source is 20 (3-4), and washing and drying after solvothermal reaction to obtain a precursor; S2, grinding the precursor, and then pyrolyzing to obtain FeNC catalyst; And S3, pickling the FeNC catalyst by adopting concentrated sulfuric acid, and then washing, suction filtering and drying to obtain the defect-containing iron monoatomic catalyst.
3. The method for preparing an acid-washing defect engineering modified iron monoatomic catalyst according to claim 2, wherein in the step S1, the zinc source is Zn (NO 3 ) 2 ·6H 2 O) and the iron source is Fe (acac) 3 .
4. The method for preparing an acid-washing defect engineering modified iron monoatomic catalyst according to claim 2, wherein in the step S1, the molar ratio of Zn 2+ to Fe 3+ is 20 (3.5-4).
5. The method for preparing an acid-washing defect engineering modified iron monoatomic catalyst according to claim 4, wherein the molar ratio of Zn 2 + 、Fe 3+ to 2-methylimidazole is 16:3:64.
6. The preparation method of the pickling defect engineering modified iron monoatomic catalyst is characterized by comprising the steps of mixing a zinc source, an iron source and methanol to obtain an A-phase solution, mixing 2-methylimidazole and methanol to obtain a B-phase solution, uniformly pouring the A-phase solution into the B-phase solution within 10-15S, continuously stirring, sealing, and standing at room temperature for 22-24 h.
7. The method for preparing the pickling defect engineering modified iron monoatomic catalyst according to claim 2, wherein in the step S2, the heating rate of pyrolysis is 4-6 ℃ per minute, the pyrolysis temperature is 800-900 ℃, the heat preservation time is 2-4 hours, argon is continuously introduced during pyrolysis, and the pyrolyzed product is ground again.
8. The method for preparing the pickling defect engineering modified iron monoatomic catalyst according to claim 2, wherein in the step S3, the concentration of concentrated sulfuric acid is 1mol/L, the concentration of FeNC catalyst in acid liquor is 500-700 mg/L, the pickling temperature is 70-90 ℃, the stirring speed is 300rpm, and the pickling time is 6h.
9. The use of the modified iron monoatomic catalyst for pickling defect engineering as claimed in claim 2 as a catalyst for advanced oxidation treatment of sewage containing organic matters.
10. The use according to claim 9, wherein the organic matter is a contaminant containing aromatic rings and heterocyclic structures, the catalyst is added at a concentration of 80-100 mg/L, and the PDS is added at a concentration of 0.2-0.3 mol/L.

Description

Modified iron monoatomic catalyst for pickling defect engineering and preparation method and application thereof Technical Field The invention belongs to the technical field of preparation of iron monoatomic catalysts, and particularly relates to an acid-washing defect engineering modified iron monoatomic catalyst, and a preparation method and application thereof. Background In recent years, the risk prevention of new pollutants is widely focused worldwide, and refractory organic pollutants (such as sulfonamide antibiotics, bisphenol A, dyes and the like) containing aromatic rings and heterocyclic structures in water body have the characteristics of strong biotoxicity, high environmental persistence, obvious bioaccumulation and the like, so that the environmental risk is hidden and the treatment difficulty is extremely high. The pollutants are poor in water solubility and stable in metabolism, the water body becomes a main environment carrier, the traditional means such as adsorption, flocculation and biological treatment are difficult to realize deep removal, long-term accumulation can form serious potential threat to the ecological system and human health, and development of efficient treatment technology has become urgent need in the environment field. Compared with the traditional treatment means, the Advanced Oxidation Process (AOPs) realizes the rapid degradation of the refractory pollutants by generating high-activity oxygen species, has the advantages of high removal efficiency, small secondary pollution and the like, and has been widely applied to refractory micro-pollutant removal and sewage deep treatment. Among them, the advanced oxidation process (PDS-AOPs) based on Peroxodisulfate (PDS) has strong stability of oxidant, wide applicable pH range, lasting oxidation capability, and can generate various high-activity species through activation, which shows unique advantages in the treatment of refractory organic pollutants, and has been studied and focused in recent years. The efficient activation of PDS is the core of the process, and the performance of the catalyst directly determines the decomposition efficiency of PDS and the degradation effect of pollutants, so that the development of a PDS activated catalyst with high performance, low cost and environmental friendliness becomes a key for promoting the engineering application of the technology. Among the PDS activated catalysts, single-atom catalysts (SACs) have been the focus of research in this field by virtue of their high atom utilization, clear active sites, excellent catalytic selectivity, and the like. Wherein, the Fe-N-C type single-atom catalyst has good potential in PDS activation due to the synergistic effect of Fe active site and N-C carrier, and the zeolite imidazole ester skeleton (ZIF-8) has the characteristics of high specific surface area, rich nitrogen source and easy formation of porous carbon skeleton after pyrolysis, thus becoming a preferable precursor for preparing the catalyst. Compared with a homogeneous catalytic material, the ZIF-8-derived Fe-N-C heterogeneous catalyst can reduce metal ion leaching, realize cyclic utilization and further reduce secondary pollution risk. However, the control range of the molar ratio of Zn 2+ to Fe 3+ in the traditional preparation process is wider, the proportion difference of different methods is larger, the metal proportion is usually insufficient in the interval of 10:1 to 500:1, the poor dispersity of Fe atoms or unstable coordination structure is easily caused, and agglomeration is easily caused, the core reasons are that ZIF-8 is a zinc-based MOF material, four ligand coordination sites of the ZIF-8 are mainly occupied by Zn 2+ and form stable Zn-N bond with 2-methylimidazole, iron ions are not regulated to enter into topological nodes of the ZIF-8 in a legal manner, are usually in the form of surface adsorption or pore canal limit, and are difficult to be used as framework components for stable coordination, the coordination stability of the 2-methylimidazole to iron is far lower than that of zinc, iron atoms are easy to be decomplexed and migrate in the pyrolysis process, zn is sublimated and removed at about 900 ℃ in the pyrolysis process, if the iron atoms are not effectively anchored by N/C matrix, the space isolation migration agglomeration is lost, meanwhile, the local concentration of iron ions is too high, and the capability of anchoring of the N/C matrix is further aggravated, and the metal aggregation is further. Meanwhile, the existing ZIF-8-derived Fe-N-C monoatomic catalyst still has obvious defects in practical application, such as high difficulty in defect site regulation and control, difficulty in accurate control of quantity and type, influence on full play of catalytic activity, easy performance attenuation in recycling due to improvement of iron atom catalytic stability, difficulty in meeting continuous requirements of practical wastewater treatment, and limi