CN-122006719-A - Magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect and regeneration method thereof

CN122006719ACN 122006719 ACN122006719 ACN 122006719ACN-122006719-A

Abstract

The invention relates to the technical field of chemical catalysis, and discloses a magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect and a regeneration method thereof, which comprises the steps of alkali treatment of porous diatomite ceramic ball carrier to form active hydroxyl, immersing the carrier in magnesium aluminum iron precursor solution, controlling heating rate to induce the in-situ directional growth of a magnesium aluminum iron hydrotalcite-like laminate array on the surface of the carrier, wherein iron elements in the laminate array are distributed in radial gradient, the invention utilizes the preferential dissolution mechanism of the edge area in the low pH environment to induce the surface passivation layer to directionally peel off, thereby realizing the self-updating of the catalytic active sites, eliminating the organic shielding effect of the active sites in the heterogeneous Fenton system, realizing the cyclic recovery of the catalytic performance on the basis of ensuring the stable structure of the filler and improving the engineering feasibility of the industrial organic wastewater treatment.

Inventors

TAN ZHIWEN
ZHOU ZHENG
CHEN GUANGYU
Zhou Shangteng
Yang Chenglian

Assignees

湖南迪亚环境工程股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260305

Claims (10)

1. A magnesium aluminum iron hydrotalcite-like catalytic filler having a pH memory effect, comprising: Porous diatomite ceramic ball carrier with 60-65% porosity and 5 density distributed on its surface To 10 Active hydroxyl groups of (a); The magnesium-aluminum-iron hydrotalcite-like layer plate array grows on the surface of the porous diatomite ceramic ball carrier, wherein the molar ratio of metal components in the magnesium-aluminum-iron hydrotalcite-like layer plate array is 3.0:1 to 3.5:1, and the percentage content of iron atoms is as follows: to 0.08, where 、 And Respectively representing the mole number of magnesium, aluminum and iron; The iron element in the magnesium aluminum iron hydrotalcite-like laminate array is gradually distributed from the center of the laminate to the edge, and the iron atom percentage concentration of the edge area is 1.2 to 1.5 times of that of the center area; The magnesium aluminum iron hydrotalcite-like compound laminate array has a non-uniform stable structure, wherein the non-uniform stable structure comprises a metastable state area caused by lattice distortion of the laminate edge, the lattice distortion rate of the metastable state area is 3-5%, and the (003) interplanar spacing of the metastable state area is increased by 0.02-0.05 nm compared with that of the central area.
2. The magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect according to claim 1, wherein the magnesium aluminum iron hydrotalcite-like laminate array grows in an oriented manner perpendicular to the surface of the porous diatomite ceramic ball carrier to form a layered array structure with a height of 500-800 nm and a thickness of 30-50 nm, and the porous diatomite ceramic ball carrier has a diameter of 2 To 10 The magnesia-alumina-iron hydrotalcite-like laminate array is distributed on the inner wall surface of the through hole and the outer surface of the porous diatomite ceramic ball carrier.
3. The magnesium aluminum iron hydrotalcite like catalytic filler having pH memory effect according to claim 1, wherein the radial distribution gradient of iron element at the edge of the magnesium aluminum iron hydrotalcite like laminate array satisfies the following formula: , wherein, Is an edge enrichment factor, the value of which is 0.25 to 0.45, Is the atomic percent concentration of iron in the edge region, Is the atomic percent concentration of iron in the central region, Is the average percentage concentration of iron atoms in the magnesium aluminum iron hydrotalcite-like laminate array.
4. The magnesium aluminum iron hydrotalcite like catalytic filler with pH memory effect according to claim 1, wherein the porous diatomite ceramic ball carrier has a specific surface area of 50 To 80 degrees The average grain diameter is 3mm to 5mm, and the active hydroxyl is the product of the porous diatomite ceramic ball carrier surface after the silicon-oxygen bond is broken by alkali treatment.
5. The magnesium aluminum iron hydrotalcite like catalytic filler having pH memory effect according to claim 2, wherein the interlayer spacing in the layered array structure is 0.76nm to 0.82nm, and the magnesium aluminum iron hydrotalcite like laminate array comprises interlayer balancing anions The loading capacity of the magnesium aluminum iron hydrotalcite-like compound laminate array on the porous diatomite ceramic ball carrier is 8-12% of the total mass of the porous diatomite ceramic ball carrier.
6. The magnesium aluminum iron hydrotalcite like catalytic filler having a pH memory effect according to claim 1, wherein the density of the magnesium aluminum iron hydrotalcite like laminate array is 2.1 To 2.4 The coverage rate of the porous diatomite ceramic ball carrier surface is 95-98%, and the lattice distortion of a metastable state area is an unbalanced state structure induced by the heating rate of 1.2-1.5 ℃ per minute in the hydrothermal reaction process.
7. The magnesium aluminum iron hydrotalcite-like catalytic filler having a pH memory effect according to claim 1, wherein the dissolution rate of the metastable region at pH 3.5 is 10 to 15 times that of the central region under the same pH condition, and the peeling of the metastable region occurs by acid-induced dissolution after the passivation layer is formed on the surface of the magnesium aluminum iron hydrotalcite-like catalytic filler having a pH memory effect.
8. The magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect according to claim 1, wherein the average grain size of the magnesium aluminum iron hydrotalcite-like laminate array is 20-40 nm, the half-peak width of the diffraction peak of the (003) crystal face is 0.35-0.50 DEG, and the iron element is isomorphously substituted for part of aluminum ions in the magnesium aluminum iron hydrotalcite-like laminate array crystal lattice in the form of positive ferric iron ions.
9. The magnesium-aluminum-iron hydrotalcite-like catalytic filler with pH memory effect according to claim 1, wherein the porous diatomite ceramic ball carrier is prepared by roasting diatomite, clay and pore-forming agent at 1000-1100 ℃, and the active hydroxyl is in infrared spectrum 3400 To 3600 The band has characteristic absorption peak, the magnesium aluminum iron hydrotalcite-like layer plate array has a space domain-limiting structure in the through pore canal of the porous diatomite ceramic ball carrier, and when the iron sites on the surface of the magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect are passivated by organic matters, the metastable state area is preferentially dissolved and drives the passivation layer to fall off under the environment with pH of 3.0-4.5.
10. A method for regenerating magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect, which is used for preparing the magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect as set forth in claim 1, and is characterized by comprising the following steps: Step S111, placing the porous diatomite ceramic ball carrier in a NaOH solution with the mass fraction of 10-15%, and reacting for 2-4 hours at 60-80 ℃ to form active hydroxyl on the surface of the carrier; S112, dissolving magnesium salt, aluminum salt and ferric salt in deionized water, preparing mixed nitrate solution with total metal concentration of 0.15-0.25 mol/L, adding urea into the mixed nitrate solution according to the metal component composition ratio, and uniformly mixing to obtain a precursor solution, wherein the total molar ratio of urea to metal ions is 4:1-5:1; Step S113, immersing the treated porous diatomite ceramic ball carrier in a precursor solution, heating to 95-110 ℃ at a constant heating rate of 1.2-1.5 ℃ per minute under a closed environment, and preserving heat for 12-24 hours to grow a magnesium aluminum iron hydrotalcite-like laminate array with lattice distortion rate and (003) increment of crystal face spacing on the surface of the carrier; Step S114, washing and drying the reaction product to obtain the magnesium-aluminum-iron hydrotalcite-like catalytic filler with the pH memory effect.

Description

Magnesium aluminum iron hydrotalcite-like catalytic filler with pH memory effect and regeneration method thereof Technical Field The invention relates to a magnesium aluminum iron hydrotalcite-like catalytic filler with a pH memory effect and a regeneration method thereof, belonging to the technical field of chemical catalysis. Background In the current advanced oxidation treatment of industrial wastewater, a heterogeneous Fenton catalytic process based on hydrotalcite belongs to a chemical and physical method, a supported magnesium aluminum iron hydrotalcite-like catalytic filler is formed by in-situ growth of hydrotalcite-like nano-sheet arrays on the surface of a porous carrier, laminate iron ions are utilized to provide active sites, and hydrogen peroxide is induced to generate strong oxidative free radicals. Under the working condition of high-concentration organic wastewater, chemical adsorption of macromolecular organic matters of wastewater and degradation intermediate products occurs on the surface of hydrotalcite-like nano-sheets, a compact passive film is formed along with local polymerization or inorganic salt deposition, the passive film physically shields active sites and blocks a reactant diffusion path, so that the catalytic efficiency of a system is attenuated along with the running time, the formation rate of the passive layer is accelerated by increasing the content of active components or increasing the specific surface area, the inactive filler is regenerated by adopting high-temperature roasting or strong acid and alkali flushing, the hydrotalcite-like layered structure collapse and the loss of active metal components are caused by lack of site selectivity, the thermal expansion mismatch between the active layer and a carrier is induced, the structural stripping and irreversible physical strength degradation increase the running cost, besides the physical structure maintenance, the existing control method also has defects in the aspect of active site updating, for example, the method for synthesizing indole compounds by catalysis of hydrotalcite catalysts is disclosed in China patent publication No. CN106179294A, the method relates to the regeneration of the inactive catalysts, the hydrotalcite-like nitric acid degradation structure is utilized to be destroyed by nitric acid degradation, and the hydrotalcite-like structure is converted into metal salt solution, and then the method is reconstructed in situ by coprecipitation method, and the active components are lost, the active components are severely destroyed, the anchoring energy level is damaged, and the skeleton is difficult to be restored by self-maintaining stable in situ, and stable in the skeleton is difficult to realize in the aspect. Therefore, how to construct a catalytic system with interface self-updating capability without losing framework stability becomes the technical problem to be solved by the invention. Disclosure of Invention In order to solve the problems in the background technology, the technical scheme of the invention is as follows, the magnesium aluminum iron hydrotalcite-like catalytic filler with the pH memory effect comprises: Porous diatomite ceramic ball carrier with 60-65% porosity and 5 density distributed on its surface To 10Active hydroxyl groups of (a); The magnesium-aluminum-iron hydrotalcite-like layer plate array grows on the surface of the porous diatomite ceramic ball carrier, wherein the molar ratio of metal components in the magnesium-aluminum-iron hydrotalcite-like layer plate array is 3.0:1 to 3.5:1, and the percentage content of iron atoms is as follows: to 0.08, where 、AndRespectively representing the mole number of magnesium, aluminum and iron; The iron element in the magnesium aluminum iron hydrotalcite-like laminate array is gradually distributed from the center of the laminate to the edge, and the iron atom percentage concentration of the edge area is 1.2 to 1.5 times of that of the center area; The magnesium aluminum iron hydrotalcite-like compound laminate array has a non-uniform stable structure, wherein the non-uniform stable structure comprises a metastable state area caused by lattice distortion of the laminate edge, the lattice distortion rate of the metastable state area is 3-5%, and the (003) interplanar spacing of the metastable state area is increased by 0.02-0.05 nm compared with that of the central area. Preferably, the magnesium aluminum iron hydrotalcite-like laminate array grows in an oriented manner perpendicular to the surface of the porous diatomite ceramic ball carrier to form a layered array structure with the height of 500-800 nm and the thickness of 30-50 nm, wherein the porous diatomite ceramic ball carrier has the diameter of 2To 10The magnesia-alumina-iron hydrotalcite-like laminate array is distributed on the inner wall surface of the through hole and the outer surface of the porous diatomite ceramic ball carrier. Preferably, the radial distribution gradie