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WO2019033695A1 - Matériau à base d'oxyde de manganèse et procédé pour la préparation de celui-ci - Google Patents

Matériau à base d'oxyde de manganèse et procédé pour la préparation de celui-ci Download PDF

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Publication number
WO2019033695A1
WO2019033695A1 PCT/CN2018/072207 CN2018072207W WO2019033695A1 WO 2019033695 A1 WO2019033695 A1 WO 2019033695A1 CN 2018072207 W CN2018072207 W CN 2018072207W WO 2019033695 A1 WO2019033695 A1 WO 2019033695A1
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Prior art keywords
manganese
oxide material
manganese oxide
mno
material according
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Chinese (zh)
Inventor
龚斌
袁招莲
刘征官
刘明彪
谢楠
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QIANDONG RARE EARTH GROUP Co Ltd
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QIANDONG RARE EARTH GROUP Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • C01G45/12—Complex oxides containing manganese and at least one other metal element

Definitions

  • the invention relates to a manganese oxide material and a method of making and using same. It belongs to the field of catalytic materials and environmental protection technology.
  • Manganese oxide is an important functional oxide material with abundant sources, low price, non-toxic and harmless, and has a wide range of applications in catalytic oxidation, heavy metal adsorption, magnetism and batteries.
  • methods for preparing manganese oxide include solid phase reaction method, hydrothermal method, sol-gel method, liquid phase precipitation method, etc. Different preparation methods can obtain manganese oxides with different crystal structure and morphology. Manganese oxides with different crystal structures and morphologies have great differences in use. The manganese oxide used in the catalyst has excellent catalytic ability due to its different morphology.
  • CO, VOCs, O 3 also caused more different concentrations and types of waste gas, wastewater, etc. in our living environment. Pollution.
  • ozone generated by copier toner heating and organic exhaust gas ozone generated by ultraviolet lamp sterilization is a strong carcinogen.
  • methods for removing these pollutants on the market mainly include biological methods, adsorption methods, plasma techniques, chemical reaction methods, photocatalytic oxidation techniques, and thermal catalytic oxidation techniques.
  • biological methods mainly include biological methods, adsorption methods, plasma techniques, chemical reaction methods, photocatalytic oxidation techniques, and thermal catalytic oxidation techniques.
  • the purification method of biological method is strong, but the rate of absorption is usually slow, and plants are prone to pathological changes; the adsorption method has high short-term efficiency, but needs to be regenerated or directly failed after adsorption equilibrium, and still needs to be carried out for the analyzed harmful substances.
  • the plasma technology method has high efficiency but generates harmful substances which are not completely oxidized, and has high cost; the chemical reaction method is fast but has a short effective period; although the photocatalytic oxidation technology has high efficiency, it generates harmful substances such as methanolic formic acid and has high cost; Thermal catalytic oxidation technology is highly efficient but the choice of catalyst is difficult.
  • Normal temperature catalytic oxidation catalysts include noble metal catalysts and non-precious metal catalysts. Due to the high price of precious metals, the development of transition metal oxide catalysts containing little or no precious metals is the current research mainstream.
  • the Chinese Patent Application Publication No. CN103506111A discloses a method for preparing a catalyst MnO 2 for removing formaldehyde and ozone at room temperature, comprising the following steps: First, preparing a water-soluble manganese salt a solution of 0.1 to 2 mol / L; second, the oxidant is formulated into a solution of 0.05 to 1 mol / L; third, the continuous rate of the solution of step 2 is uniformly added dropwise to the solution of step 1; fourth, the production of MnO 2 The suspension is aged for 1 to 10 hours; the fifth, the precipitate obtained after aging is washed with water for 1 to 5 times, and after suction filtration, it is dried at 105 ° C, and then calcined at 200 to 300 ° C for 2 to 10 hours.
  • the vested MnO 2 catalyst technical solution.
  • the catalyst MnO 2 prepared by the method was simultaneously decomposed into harmful H 2 O and CO 2 in the polluted air at room temperature, with no harmful by-products, formaldehyde and ozone efficiency. High advantage "technical effect.
  • MnOx Mn-based metal oxide
  • VOCs volatile organic compounds
  • This application discloses "dissolving KMnO4 and an inorganic liquid acid in a volume of deionized water to form a solution 1; diluting a certain amount of H 2 O 2 with deionized water to form a solution 2; at room temperature, dropping the solution 2 dropwise Adding to the solution 1; aging the resulting precipitate after aging overnight, filtering, washing, drying and high-temperature calcination, the desired MnOx catalyst can be obtained, and the method has the advantages of simple and rapid, and can be avoided.
  • the hydrothermal synthesis method and the direct precipitation method are faced with the problems of high synthesis temperature, long time, and waste of waste water; and MnOx materials with multi-stage structure can be synthesized, and the larger comparison area is beneficial to the catalytic combustion reaction of VOCs.
  • the surface is carried out. In the low-temperature catalytic combustion of toluene and formaldehyde, the synthesized MnOx has achieved the desired catalytic effect.
  • WO 2012/167280 A1 discloses the name "Manganese oxide and activated carbon for removing particles, volatile organic compounds or ozone from gases” (MANGANESE OXIDE AND ACTIVATED CARBON) FIBERS FOR REMOVING PARTICLE, VOC OR OZONE FROM A GAS) Patent application.
  • This application discloses "a device for catalytic oxidation to reduce the content of volatile organic compounds (VOC) in gases, including manganese oxide (MnOx) catalysts.
  • This manganese oxide (MnOx) catalyst can catalyze formaldehyde completely at room temperature. It is converted to CO 2 and water vapor.
  • the manganese oxide (MnOx) catalyst itself is not consumed.
  • the application also discloses a device for removing particulate matter and volatility from a gas by an activated carbon filter (ACF) during periodic regeneration.
  • the invention discloses a method for preparing the manganese oxide catalyst, comprising: mixing a manganese salt and a permanganate solution at a molar ratio of about 2:3 to form a black suspension, washing and filtering the precipitate, and heating the precipitate. It can be converted into a powder.
  • the precipitate is manganese oxide.
  • the heating step comprises heating the precipitate to a temperature equal to or greater than 50 degrees C.
  • the heating step comprises bringing the temperature of the precipitate to or above 100 °C.
  • the invention discloses a method for reducing volatile organic compound (VOC) content from a gas comprising "passing a gas containing one or more gaseous VOCs through a MnOx catalyst such that the content of volatile organic compounds in the gas is reduced”. And the use of manganese oxide catalysts as a component of building coating materials. "In the air contact, formaldehyde in the air is decomposed. In some embodiments of the invention, such components are applied to the outside/outside or inside. / Internal coating is very useful. In terms of buildings, in some inventions, it is a component of paint.
  • Manganese oxide catalyst can be added to the paint, it is applied to the internal or external plaster wall surface. Natural The air movement causes the air to contact the surface of the coating to catalyze the decomposition of formaldehyde. In some embodiments of the invention, it is applied as an ingredient to the surface of a building, which is the surface of a wall. In this case, indoor air requires only a large amount of catalyst coating material in air purification, and no fan is required. In some inventions, the catalyst is applied to a particle filter, and the airflow extracted from the interior of the building is filtered from the particles. Technologies such as passing through and then returning to the interior of the building have achieved technologies such as effective reduction of volatile organic compounds (VOC) at room temperature. effect.
  • VOC volatile organic compounds
  • the object of the present invention is to overcome the above drawbacks of the prior art, and the technical solution of the present invention is:
  • a manganese oxide material having a spherical morphology composed of fiber rods including manganese dioxide, the manganese dioxide comprising a skeleton structure of ⁇ -MnO 2 and/or amorphous manganese dioxide.
  • the crystalline structure of the manganese oxide material comprises weakly crystalline ⁇ -MnO 2 and/or amorphous manganese dioxide.
  • the manganese oxide material composition further includes divalent manganese, and the divalent manganese exists in a form comprising solid solution and/or adsorption, that is, doped with a divalent manganese compound, and divalent manganese.
  • the ratio to tetravalent manganese is 0 ⁇ Y (Mn 2+ ) / Y (Mn 4 + ) ⁇ 1.
  • the Y(Mn 2+ ) is a mass fraction of divalent manganese in the manganese oxide material
  • the Y(Mn 4+ ) is a mass fraction of the tetravalent manganese in the manganese oxide material.
  • the manganese oxide material has a T Mn of 10.88 to 68.37 wt% based on the manganese element, and the T Mn is a total mass fraction of manganese in terms of an element.
  • the T Mn is from 34.82 to 55.45 wt%.
  • the manganese dioxide comprises a weak crystalline ⁇ -MnO 2 .
  • the card number of the weak crystal ⁇ -MnO 2 detected by XRD is JCPDS No. 44-0141.
  • the weak crystal ⁇ -MnO 2 and/or the amorphous manganese oxide in the manganese oxide material gradually tends to ⁇ -MnO 2 as the temperature increases.
  • the weak crystalline ⁇ -MnO 2 and / or amorphous manganese oxide can then transition to the ⁇ -MnO 2 into weakly crystalline ⁇ -MnO 2 and / or amorphous manganese oxide .
  • the manganese oxide material has a heat stable temperature of >535 °C.
  • the heat stable temperature is ⁇ 540 °C.
  • the manganese oxide material has a heat stable temperature of ⁇ 600 °C.
  • other metal elements are further included, and the other metal elements are mainly located inside the manganese oxide material.
  • the molar ratio of the other metal element to the manganese element is 0.1 to 0.67.
  • the molar ratio of the other metal element to the manganese element is preferably from 0.1 to 0.5, more preferably from 0.12 to 0.38.
  • the manganese oxide material further includes other metal elements A and/or B having a chemical formula of AyBzMn 2+ xMn 4+ 1-xO 2 .
  • A is a metal element of the main group
  • B is a transition metal element other than manganese, 0.10 ⁇ x ⁇ 0.45, y ⁇ 0.507, and z ⁇ 0.67.
  • the A is preferably an alkali metal element and/or an alkaline earth metal element.
  • the alkali metal element is preferably K.
  • the alkaline earth metal element is preferably Mg.
  • the B is preferably at least one of Cu and rare earth. More preferably, the rare earth is La and/or Ce.
  • the main group metal element further includes Sn or the like.
  • the transition metal also includes Co, Ag, and the like.
  • the other metal elements are mostly located inside the manganese oxide material. That is, the content of other metal elements on the surface of the manganese oxide material ⁇ the total content of other metal elements in the manganese oxide material. Preferably, the content of other metal elements on the surface of the manganese oxide material / the total content of other metal elements in the manganese oxide material is ⁇ 0.5. More preferably, the content of other metal elements on the surface of the manganese oxide material / the total content of other metal elements in the manganese oxide material is ⁇ 0.3.
  • the water absorption amount is 1 to 18% by weight, and the water absorption amount is preferably ⁇ 8% by weight.
  • the water absorption amount (W 2 - W 1 ) / W 1 * 100%, wherein W 1 is the weight of the manganese oxide material after drying at 250 ° C for 4 h, and W 2 is the manganese oxide material dried at 250 ° C for 4 h. Thereafter, the weight was allowed to stand in a closed vessel having a saturated aqueous solution of NH 4 NO 3 at a temperature of 27 ° C for 2 hours.
  • the spherical structure has a diameter of 0.9 to 2.2 ⁇ m.
  • the nanofiber rod has a diameter of 10 to 50 nm.
  • the spherical structure has a diameter of 0.9 to 1.92 ⁇ m. More preferably, the spherical structure has a diameter of 0.9 to 1.55 ⁇ m.
  • the nanofiber rod has a diameter of 10 to 42 nm. More preferably, the nanofiber rod has a diameter of 15 to 26 nm.
  • the specific surface is 85 to 300 m 2 /g, the average pore diameter is 1.9 to 8 nm, and the pore volume is 0.1 to 0.5 cm 3 /g.
  • the specific surface is preferably 130 to 220 m 2 /g.
  • the lattice oxygen/adsorbed oxygen is 1.5.
  • the ⁇ -MnO 2 skeleton structure, the 16-26 nm diameter nanofiber rod has a spherical structure with a diameter of 1.09 to 1.55 ⁇ m;
  • the main phase of the manganese dioxide is a weak crystal ⁇ -MnO 2 and amorphous
  • the manganese oxide, the weak crystal ⁇ -MnO 2 PDF card number is JCPDS No. 44-0141.
  • Y(Mn 2+ )/Y(Mn 4+ ) 0.48; specific surface area is 257.33m 2 /g, pore diameter is 5.93nm, pore volume is 0.40cm 3 /g; K, La, Ce, Cu and other non-manganese
  • the molar ratio of the metal element to the manganese element is 0.36; wherein most of the non-manganese metal elements such as K, La, Ce, and Cu are located inside the material; the heat stable temperature is 550 °C.
  • the invention also provides a preparation method of a manganese oxide material, comprising:
  • Precipitate A is prepared by mixing soluble divalent manganese salt with manganese dioxide according to mole 0 ⁇ soluble divalent manganese salt/manganese dioxide ⁇ 1, or mixing excess divalent manganese compound with high-valent manganese compound to prepare precipitate A Then, an anion is added to obtain a precipitate B to obtain a manganese oxide material; then an anion is added to stir to obtain a precipitate B, thereby obtaining a manganese oxide material, an excess portion of the divalent manganese compound and a tetravalent manganese compound formed by the reaction.
  • the molar ratio is less than 1, and the high-valent manganese compound is at least one of a positive pentavalent manganese compound, a normal hexavalent manganese compound, and a positive heptavalent manganese compound.
  • One of the preferred technical solutions for the preparation method of the manganese oxide material of the present invention is that the anion is at least one of Cl - , NO 3 - , and SO 4 2- , and the anion concentration is ⁇ 0.1 mol/L.
  • a further preferred embodiment of the method for preparing the manganese oxide material of the present invention further comprises mixing the precipitate B with another metal salt solution to control the pH of 7 to 9, to obtain a precipitate C.
  • the other metal salt is preferably at least one of an alkali metal, an alkaline earth metal, and a transition metal salt.
  • the alkali metal is preferably K
  • the alkaline earth metal is preferably Mg
  • the transition metal is preferably at least one of Cu, Co, Ag, and rare earth
  • the rare earth is preferably La and/or Ce.
  • the other metal salt is preferably at least one of a nitrate, a sulfate, a chloride, and an acetate.
  • Other metal salts also include soluble tin salts.
  • a further preferred embodiment of the method for producing a manganese oxide material according to the present invention further comprises the steps of filtering, drying, forming and/or calcining the precipitate B or the precipitate C.
  • a further preferred embodiment of the method for preparing a manganese oxide material according to the present invention has a temperature of 20 to 80 ° C and a pH of 7 when the precipitate A is prepared.
  • manganese dioxide is prepared according to the reaction formulas (a) to (f) described later.
  • a further preferred embodiment of the method for preparing a manganese oxide material according to the present invention has a pH of ⁇ 10 when preparing manganese dioxide.
  • a further preferred embodiment of the method for preparing a manganese oxide material according to the present invention comprises dissolving 169.3 parts of MnCO 3 in a suspension, adding 157.6 parts of K 2 MnO 4 , maintaining the temperature at 50 ° C, controlling the pH 8-10, and stirring for 4 hours.
  • the concentration of SO 4 2- was adjusted to about 1 mol/L with sulfuric acid and stirred for 1 h.
  • CuSO 4 , LaCl 3 , and CeCl 3 were added , adjusted to pH 7-8, stirred for 2 hours, washed, filtered, and dried to obtain a manganese oxide material.
  • the invention also provides a method of using the manganese oxide material: the manganese oxide material is used as a catalyst and/or adsorbent.
  • the method for using the manganese oxide material of the present invention is preferably one of technical solutions for catalytically oxidizing CO and/or O 3 , VOCs.
  • the method of using the manganese oxide material of the present invention is preferably one of the technical solutions, wherein the manganese oxide material is used at a relative humidity of ⁇ 55%.
  • the method of using the manganese oxide material of the present invention is preferably one of the technical solutions for adsorbing heavy metal ions.
  • the invention also provides a purification device comprising an inlet 1, a purification component 3 and an outlet 6.
  • the inlet 1, the purification member 3 and the outlet 6 are sequentially arranged in the order in which the gas flows; wherein the manganese oxide material of the present invention is installed in the purification member 3.
  • One of the preferred technical solutions of the air purifying device according to the present invention further comprises a fan 4, the fan 4 being located between the inlet 1 and the outlet 6.
  • a filter member is disposed between the inlet 1 and/or the outlet 6 and the purification member 3.
  • the inlet 1 is located at the top.
  • the inlet 1 is located on the front side and/or the side.
  • the outlet 6 is located at the bottom.
  • the inlet 1 and the outlet 6 are interchangeable.
  • Still another preferred embodiment of the air purifying apparatus of the present invention further includes a control device for controlling the interchange of the inlet 1 and the outlet 6.
  • Manganese dioxide is doped with divalent manganese compound, Y(Mn 2+ )/Y(Mn 4+ ) ⁇ 1, so that manganese oxide material has a large number of vacancies and defects, and has good catalytic activity. It is a metal oxide type material that can be used directly or on other carriers. It is doped with other metal elements, further increasing the active site and vacancy defects, showing better performance. The doped transition element is superior to the doped first main group element. Has excellent catalytic properties.
  • Oxygen exists in many forms to facilitate the migration of oxygen.
  • the spherical structure composed of nanofiber rods is not only beneficial for increasing the specific surface, but also provides strong support for the surface hydroxyl groups. Therefore, it exhibits excellent catalytic performance and good specific properties such as good adsorption, hydrophobicity and easy regeneration.
  • the manganese oxide material is a weak crystalline and/or amorphous manganese oxide material, and no significant alkali metal, copper oxide and rare earth oxide peaks are detected by XRD. Moreover, the structure of the material after firing at 540 ° C or above does not change, and has good thermal stability, which is favorable for material regeneration. No transition of MnO 2 to Mn 2 O 3 was observed during the crystal transformation, and only the transition of MnO 2 to Mn 3 O 4 was observed.
  • the preparation method of the invention is environmentally friendly and simple, and has a wide range of raw materials, low cost, and easy industrialization.
  • the inlet and outlet of the purification device can be interchanged to reduce the dirt such as dust on the purification component or the filter component, reduce the resistance and prolong the life of the purification device.
  • Example 1 is an X-ray diffraction (XRD) pattern of a manganese oxide material prepared in Example 1.
  • XRD X-ray diffraction
  • Example 2 is an 8K-fold magnified SEM image of the manganese oxide material prepared in Example 1.
  • Example 3 is a 50K-fold enlarged SEM image of the manganese oxide material prepared in Example 1.
  • Example 4 is an EDS diagram of the manganese oxide material prepared in Example 1.
  • Figure 5 is an XPS chart of the manganese oxide material prepared in Example 1.
  • Fig. 6 is a graph showing the catalytic oxidation activity of carbon monoxide as a manganese oxide material prepared in Example 1 (Table 2, No. 1).
  • Fig. 7 is a graph showing the catalytic oxidation activity of formaldehyde of the manganese oxide material prepared in Example 1 (Table 2, No. 4).
  • A is a manganese oxide material I dried at 50 ° C for 24 h; B is a manganese oxide material I calcined at 540 ° C for 2 h; C is Manganese oxide material I was calcined at 600 ° C for 2 h; D was manganese oxide material I was calcined at 540 ° C for 2 h and then used for 1 year at room temperature.
  • A is a manganese oxide material II dried at 50 ° C for 24 h; B is a manganese oxide material II calcined at 540 ° C for 2 h; C is Manganese oxide material II was calcined at 600 ° C for 2 h; D was manganese oxide material II was calcined at 540 ° C for 2 h and then used for 1 year at room temperature.
  • Figure 10 is an XRD pattern of the manganese oxide material prepared in Example 3, wherein A is a manganese oxide material dried at 50 ° C for 24 h; B is a manganese oxide material dried at 400 ° C for 2 h; C is a manganese oxide The material was dried at 500 ° C for 2 h.
  • Figure 11 is an SEM image of the manganese oxide material I prepared in Example 2.
  • Figure 12 is an SEM image of the manganese oxide material prepared in Example 3.
  • Figure 13 is an XRD chart of the manganese oxide material prepared in Example 7 after drying at 50 ° C for 24 hours.
  • Example 14 is an SEM image of a manganese oxide material prepared in Example 7.
  • Figure 15 is a flow chart showing the purification apparatus of Examples 9 and 11.
  • Figure 16 is a schematic view of the purification apparatus of Examples 9 and 11.
  • Mn(OH) 3 is prone to disproportionation: Mn(OH) 3 ⁇ Mn(OH) 2 +MnO 2 (d)
  • Mn 3+ is prone to disproportionation: Mn 3+ ⁇ Mn 2+ + MnO 2 (e)
  • MnO 4 2- cannot be stably present: MnO 4 2- ⁇ MnO 4 - + MnO 2 (f)
  • Mn (OH) 2 dissociates: Mn (OH) 2 + H + ⁇ Mn 2+ + H 2 O (g)
  • Mn 2+ by manganese dioxide in the manganese oxide material prepared by the invention is similar to the adsorption of other transition metal ions by oxides such as iron and aluminum, and belongs to the specific adsorption.
  • These Mn 2+ are oxidized to Mn 4+ by self-catalysis after being adsorbed by manganese dioxide, and the original internal Mn 4+ is reduced to Mn 2+ , thereby generating new defects inside; or Mn 2+ Diffusion into the crystal lattice to form a solid solution, resulting in new defects; or Mn 2+ replacement Mn 4+ on the lattice (manganese dioxide has isomorphous substitution properties), resulting in new defects.
  • manganese oxide material prepared by the invention Y(Mn 2+ )/Y(Mn 4+ ) ⁇ 1, divalent manganese doping (doping form different valence states of the same element) enters the inside of manganese dioxide, forming A stable phase with a specific structure (corresponding to the dissolution of Mn 2+ in a manganese dioxide solid to form a solid solution). Due to the doping of Mn 2+ , a large number of new defects are generated, which increase the oxygen escaping ability and reversibility, so that the manganese oxide material exhibits better catalytic activity and lifetime.
  • the manganese oxide material prepared by the invention has a large amount of divalent manganese doped into the material (the ionic radius of Mn 2+ is larger than that of Mn 4+ ), so that the ion exchange performance of the material is improved. Thereby, the ion exchange type, the number and the rate are also improved, and the rare earth ion doping with a large ionic radius is also realized. After the introduction of other metal ions, the material exhibits better catalytic and other effects.
  • the content of each metal element detected by ICP and the chemical composition of the surface of the manganese oxide material measured by electron probe analysis (EDS) are shown in Table 1 (all percentages of the specification are weight percentages unless otherwise specified).
  • the molar ratio of other metal elements such as K, Na, Cu, La, and Ce to the manganese element is 0.36.
  • the ratio of copper to manganese and the content of rare earth elements are low, the resource utilization rate is high, and the cost is lower.
  • the preparation method is environmentally friendly and simple, easy to obtain raw materials, low in cost, and easy to realize industrialization; the obtained manganese oxide material has strong adsorption and ion exchange capacity, and can be exchanged with various metal elements.
  • the expression is K 0.06 Na 0.18 La 0.02 Ce 0.02 Cu 0.08 Mn 2+ 0.325 Mn 4+ 0.675 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the lattice (manganese dioxide has isomorphous substitution properties), causing most of the Mn 2+ to enter Internally, divalent manganese is doped (the doping form is a different valence state of the same element). Most of the divalent manganese enters the inside of the manganese dioxide, forming a stable phase with a specific structure (corresponding to the dissolution of divalent manganese in the manganese dioxide solid to form a solid solution), resulting in a large number of new defects.
  • the water absorption of the manganese oxide material is 5%, indicating that the hydrophobicity is good, so that the manganese oxide material has high catalytic activity and long service life under the condition of high humidity at room temperature, and exhibits excellent moisture resistance and catalytic ability (see Table 2 for details). ).
  • the main phase is weak crystal ⁇ -MnO 2 (JCPDS No. 44-0141) and amorphous manganese dioxide.
  • the diffuse peak in the spectrum is amorphous manganese dioxide, and the weak diffraction peak around 38° is ⁇ -MnO 2 .
  • the crystal structure is basically unchanged with increasing temperature, no characteristic peak of Mn 2 O 3 or Mn 3 O 4 is found, and the heat stable temperature of the manganese oxide material (heat stable according to the present invention) Temperature refers to the highest processing temperature before the material structure changes, that is, the XRD pattern shows the highest processing temperature experienced before the Mn 2 O 3 or Mn 3 O 4 , MnO characteristic peak, and the decomposition temperature of the manganese oxide material should not be lower than the present invention.
  • the heat stable temperature is the same as 550 ° C.
  • the dispersion peak gradually weakens and the characteristic peak of ⁇ -MnO 2 gradually becomes stronger, indicating that the crystal phase structure gradually changes to ⁇ -MnO 2 with increasing temperature.
  • the dispersion peak is more pronounced and the crystallization is more obvious, but the characteristic peak of Mn 3 O 4 (JCPDS No. 24-0734) appears near 36 ° from 600 ° C, indicating that partial phase transition has occurred.
  • decomposition The crystal phase rises to 800 °C and the characteristic peak of Mn 3 O 4 is very obvious, but there is still a large amount of amorphous manganese dioxide.
  • the XRD results did not show the characteristic peaks of rare earth, copper and divalent manganese, indicating that most of these doped substances exist inside the manganese oxide.
  • the structure of the manganese oxide material calcined at 550 ° C has not changed, and has good thermal stability, which is favorable for its regeneration.
  • MnO 2 is decomposed into Mn 2 O 3 at 535 ° C; Mn 2 O 3 is converted to Mn 3 O 4 at 940 ° C; and Mn 3 O 4 is converted to MnO at 1000 ° C or higher.
  • Manganese oxide material of the present embodiment Preparation of thermal decomposition process, due to the impact of a large number of divalent manganese is not observed at 550 °C for when the Mn 2 O 3, also was not observed after the Mn 2 O 3, only 600 Mn 3 O 4 begins to appear at °C. Therefore, the known properties of manganese dioxide are changed due to the presence of a large amount of divalent manganese.
  • the skeleton structure of the manganese oxide material prepared in the present embodiment is a manganese dioxide structure in which a plurality of elements including divalent manganese are doped to form a solid solution. Due to the doping of various elements, especially the doping of Mn 2+ , the type of oxygen (such as lattice oxygen, adsorbed oxygen, etc.) is increased, the escape ability of lattice oxygen is improved, and various forms of oxygen conversion are realized. The reversibility reduces the activation energy of the reaction, thereby increasing the catalytic activity of the manganese oxide material.
  • SEM Scanning electron microscopy
  • manganese oxide material is a spherical structure with a large number of 16 ⁇ 26nm nanofiber rods with a diameter of 1.09 ⁇ 1.55 ⁇ m. It is small and uniform in size, good in dispersion and high in activity.
  • the most important surface property of manganese dioxide is that it has a large number of surface hydroxyl groups. These surface hydroxyl groups are not only an important source of surface charge, surface coordination and the like, but also exhibit a balanced structure in different acid-base media.
  • the spherical structure composed of the nanofiber rods is not only beneficial for increasing the specific surface, but also provides strong support for the surface hydroxyl groups. Therefore, it exhibits excellent catalytic performance and good specific properties such as good adsorption, hydrophobicity and easy regeneration.
  • the manganese oxide material prepared in this embodiment has a structure of ⁇ -MnO 2 and amorphous manganese dioxide, and the doped divalent manganese is mainly present in the manganese oxide material, and the average valence of the manganese element is biased.
  • Heating to 550 ° C failed to measure the decomposition of MnO 2
  • heating to 600 ° C began to appear Mn 3 O 4 characteristic peak, indicating that the manganese oxide material prepared by the present invention is not a simple mixture of manganese dioxide and manganese monoxide, nor is it the usual meaning Manganese dioxide. Due to the interaction between divalent manganese and manganese dioxide, it has higher thermal stability temperature (or decomposition temperature) than ordinary manganese dioxide.
  • Test A A certain amount (W, g) of the manganese oxide material obtained was made into a cylindrical shape, and a catalytic performance test was carried out in a reaction apparatus having a diameter of D (mm). The catalytic performance test results are shown in Table 2:
  • Test B The obtained manganese oxide material was subjected to heavy metal adsorption test after drying to remove water:
  • the manganese oxide material prepared in this embodiment has strong adsorption and ion exchange capacity and can be exchanged with various metal elements. Can handle heavy metal ion contaminants.
  • Test C The prepared manganese oxide material is subjected to drying and removing water, and then subjected to liquid VOCs adsorption decomposition test:
  • the purged manganese oxide material was further circulated for toluene adsorption and decomposition tests, and the test results are shown in Table 4.
  • the manganese oxide material prepared in this embodiment can treat both gaseous organic pollutants and organic pollutants in liquids. After recycling, it can be reused after simple treatment, which is economical and environmentally friendly.
  • Test D The prepared manganese oxide material was calcined at 550 ° C for 2 h and then filled in an air purifier for the purification of formaldehyde (concentration of about 0.15 ppm) in a newly renovated house. After 8 hours of continuous use, the formaldehyde concentration in the house was reduced. 0.02ppm or so. Take a small amount of manganese oxide material for about 1 year for XRD detection. It can be seen from Fig. 1 that the manganese oxide material is weakly ⁇ -MnO 2 and amorphous manganese dioxide after calcination at 550 ° C for 2 h; the dispersion peak is weaker and the ⁇ -MnO 2 characteristic peak is more obvious than the normal temperature drying.
  • ⁇ -MnO 2 Part of the amorphous state is converted to ⁇ -MnO 2 .
  • the XRD pattern is basically restored to normal temperature, and there is a broad dispersion peak and a diffraction peak of about 38° is weak, indicating that ⁇ -MnO 2 in the manganese oxide material is converted into weak crystal ⁇ -MnO 2 and non- Crystalline manganese dioxide.
  • Test E The prepared manganese oxide material was subjected to wastewater COD treatment and comparative test:
  • the manganese oxide material prepared in this embodiment has excellent catalytic and other performance properties due to its unique morphology and multi-element doping, especially the doping of the same element including divalent manganese.
  • each metal element of manganese oxide materials I and II by ICP is shown in Table 6.
  • the active site and the vacancy defect are increased to exhibit more excellent catalytic activity.
  • Y(Mn 2+ )/Y(Mn 4+ ) 0.18 of the manganese oxide material I and the manganese oxide material II were measured.
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • a part of Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, eventually causing most of the Mn 2+ divalent manganese to enter the interior.
  • the water absorption amount of the manganese oxide material I was measured to be 20%.
  • the microscopic features are spherical, with a diameter of about 1.12 to 1.50 ⁇ m and a nanofiber size of 19 to 26 nm.
  • the specific surface area was 300.45 m 2 /g.
  • the average pore diameter was 7.26 nm and the pore volume was 0.49 cm 3 /g.
  • the lattice oxygen/adsorbed oxygen was 1.15 by XPS analysis.
  • the most important surface property of manganese dioxide is that it has a large number of surface hydroxyl groups. These surface hydroxyl groups are not only an important source of surface charge, surface coordination and the like, but also exhibit a balanced structure in different acid-base media.
  • the spherical structure composed of the nanofiber rods is not only beneficial for increasing the specific surface, but also provides strong support for the surface hydroxyl groups. Therefore, it exhibits excellent catalytic performance and good specific properties such as good adsorption, hydrophobicity and easy regeneration.
  • the water absorption of manganese oxide material II was 19.7%; the microscopic morphology was a spherical structure of 1.12 to 1.50 ⁇ m composed of nanofibers of 15 to 25 nm; the specific surface area was 285.54 m 2 /g; the average pore diameter was 7.18 nm. The capacity is 0.48 cm 3 /g.
  • the lattice oxygen/adsorbed oxygen was 1.2 by XPS analysis.
  • the manganese oxide material II is mainly a copper element substituted for a part of the potassium element in the manganese oxide material I.
  • the molar content of other elements is basically unchanged. Since Cu 2+ is higher than the K + valence state, the adsorbed oxygen is more easily converted into lattice oxygen.
  • the XRD results show that the spectra of manganese oxide material I and manganese oxide material II are basically the same with temperature: in the range of 50-540 °C, the crystal structure is basically unchanged with the increase of temperature, the main phase is The weak crystal ⁇ -MnO 2 (JCPDS No. 44-0141) did not exhibit characteristic peaks of Mn 2 O 3 or Mn 3 O 4 , and showed no characteristic peaks of other metal element compounds such as potassium and divalent manganese compounds.
  • the structure of the material after calcination above 540 °C has not changed, the thermal stability temperature is 540 ° C; has good thermal stability, which is conducive to the regeneration of materials. After 600 ° C, the characteristic peaks of Mn 3 O 4 are very significant. No Mn 2 O 3 was observed during the crystal form change.
  • the manganese oxide material I and the manganese oxide material II were calcined at 540 ° C for 2 h, and then tested according to the test D of Example 1. And take a small amount of materials after long-term use for XRD detection.
  • the spectrum D and the map A are basically the same, and the diffraction peak of about 36° disappears in the spectrum D, indicating that the ⁇ -MnO 2 after long-term use can be converted into the weak crystal ⁇ -MnO 2 .
  • the spectrum B is a weak crystal ⁇ -MnO 2 ; with respect to the spectrum A, the characteristic peak of the ⁇ -MnO 2 in the spectrum B is more pronounced, and a partial transition to ⁇ -MnO 2 occurs.
  • Map D is similar to map A. The diffraction peak around 36° disappears in map D, indicating that the transformed ⁇ -MnO 2 can be converted into weak crystal ⁇ -MnO 2 .
  • the manganese oxide material prepared in this embodiment Mn 2+ is mainly present inside.
  • the manganese dioxide in the manganese oxide material was heated to 540 ° C and the MnO 2 decomposition product was not detected. Heating to 600 ° C, the characteristic peak of Mn 3 O 4 is obvious. It is indicated that the manganese oxide material prepared by the invention has a structure of weakly crystalline ⁇ -MnO 2 and has a higher heat stable temperature (decomposition temperature) than ordinary manganese dioxide, and is not a simple mixture of manganese dioxide and manganese monoxide.
  • the skeleton structures of the manganese oxide material I and the manganese oxide material II are both manganese dioxide structures (solid solutions doped with various elements). Due to the doping of various elements, especially the doping of Mn 2+ , the type of oxygen (such as lattice oxygen, adsorbed oxygen, etc.) is increased, the escape ability of lattice oxygen is increased, and various forms of oxygen are converted. The reversibility reduces the activation energy of the reaction, thereby increasing the catalytic activity.
  • the prepared manganese oxide material was tableted and subjected to a catalytic performance test.
  • Test A 50 g of each of manganese oxide material I and manganese oxide material II were respectively placed in a fixed-bed reactor of 30 mm in diameter, and a mixed gas of 250 ppm CO was carried in air having a relative humidity of 80 to 85%, respectively, at a reaction temperature of 85. Under the condition of °C and GHSV5000h -1 , the CO concentration of the outlet was continuously tracked for 1 h to determine the catalytic oxidation ability of each manganese oxide material to CO. The catalytic conversion rate of manganese oxide material I to CO was determined to be 90.5%; the catalytic conversion rate of manganese oxide material II to CO was 100%.
  • manganese oxide material I has good catalytic activity.
  • the manganese oxide material II doped with a similar composition of copper has a catalytic conversion rate of up to 100% and a better catalytic activity.
  • MnCl 2 336.4 parts were dissolved in deionized water. The pH was adjusted to 10 with NH 3 ⁇ H 2 O at 20 ° C, and hydrogen peroxide was added dropwise with stirring until substantially no foam was produced. Then, it was mixed with 338.4 parts of MnSO 4 ⁇ H 2 O and the pH of the system was adjusted to 7.5, and stirred at room temperature for 8 hours. Then, the concentration of SO 4 2- is adjusted to about 0.1 mol/L with sulfuric acid and ammonium sulfate, stirred at normal temperature for 3 hours, washed and dried by filtration to obtain a manganese oxide material.
  • the use of sulfuric acid in the adjustment of the sulfate concentration can reduce or eliminate the impurity Mn(OH) 2 . Because Mn(OH) 2 is easily hydrated, the water absorption of manganese oxide is high, which affects the performance of manganese oxide.
  • the use of sulfuric acid and ammonium sulfate to adjust the sulfate concentration can form a buffer solution, which is conducive to the stability of the system.
  • the T Mn was 68.37%.
  • the expression is Mn 2+ 0.41 Mn 4+ 0.59 O 2 . Due to Mn 2+ doping, the prepared manganese oxide material has a large number of defects and has good catalytic ability. After Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, etc., causing most of the Mn 2+ to enter the interior, resulting in divalent manganese doping, A stable phase with a specific structure is formed, resulting in a large number of new defects inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution. At the same time, in order to maintain the structure of manganese dioxide after the lattice oxygen escapes, the adsorbed oxygen is converted into lattice oxygen. Thereby, the oxygen escaping ability and reversibility are increased, so that the manganese oxide material exhibits better catalytic activity.
  • the water absorption of the manganese oxide material was measured to be 23%.
  • the size of the spherical structure is about 0.94 to 1.12 ⁇ m, and the size of the nanofiber is about 32 to 42 nm.
  • the specific surface area was 185.44 m 2 /g, the average pore diameter was 2.10 nm, and the pore volume was 0.15 cm 3 /g.
  • the lattice oxygen/adsorbed oxygen is 1.2.
  • the spherical structure has small size, good dispersion and good activity.
  • the main phase of the manganese oxide material is amorphous manganese dioxide as determined by XRD.
  • the crystal structure is basically unchanged with the increase of temperature, the main phase is amorphous manganese dioxide; the diffraction peak in the spectrum is the conventional amorphous diffraction peak, and the peak intensity is very weak;
  • the temperature rises the spectrum does not change significantly, and the characteristic peak of Mn 2 O 3 or Mn 3 O 4 does not appear, and the heat stable temperature of the material is 400 °C.
  • the crystallization was remarkable.
  • the crystal phase increased to 500 ° C, and the characteristic peak of Mn 3 O 4 (JCPDS No. 24-0734) was obvious. No Mn 2 O 3 was observed during the crystal form change.
  • the XRD test results showed no characteristic peak of the divalent manganese compound.
  • Mn 2+ is mainly present inside the manganese oxide material. Heating to 500 ° CMn 3 O 4 characteristic peaks are obvious.
  • the skeleton structure of the manganese oxide material prepared in this embodiment is doped with divalent manganese to form an amorphous manganese dioxide structure. Due to the doping of divalent manganese, the type of oxygen (such as lattice oxygen, adsorbed oxygen, etc.) is increased, the escape ability of lattice oxygen and the reversibility of various forms of oxygen interconversion are increased, and the activation energy of the reaction is lowered. Thereby increasing the catalytic activity of the manganese oxide material.
  • the type of oxygen such as lattice oxygen, adsorbed oxygen, etc.
  • Test A The prepared manganese oxide material was tableted and subjected to a catalytic performance test.
  • Test B The manganese oxide material obtained in the present example was subjected to a heavy metal adsorption test according to the method described in Test B of Example 1, and the measurement results are shown in Table 7.
  • the T Mn was 10.88% and the Ce content was 18.55%.
  • the molar ratio of Ce to manganese is 0.67. After doping with rare earth elements, the active sites and vacancy defects are increased to exhibit excellent catalytic activity.
  • the chemical expression is Ce 0.67 Mn 2+ 0.1 Mn 4+ 0.9 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, causing most of the Mn 2+ to enter the interior, resulting in doping of divalent manganese, forming A stable phase with a specific structure causes a large number of new defects to be generated inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution. At the same time, in order to maintain the structure of manganese dioxide after the lattice oxygen escapes, the adsorbed oxygen is converted into lattice oxygen. Thereby, the oxygen escaping ability and reversibility are increased, so that the manganese oxide material exhibits better catalytic activity.
  • the water absorption of the manganese oxide material was measured to be 15%.
  • the main phase structure was amorphous manganese dioxide by XRD, and there was no characteristic peak of Mn 2 O 3 or Mn 3 O 4 , and the heat stable temperature was 600 °C.
  • the XRD results showed no significant peaks of rare earth compounds and divalent manganese compounds. Due to the doping of divalent manganese, the type of oxygen (such as lattice oxygen, adsorbed oxygen, etc.) is increased, the escape ability of lattice oxygen and the reversibility of various forms of oxygen interconversion are increased, and the activation energy of the reaction is lowered. , thereby increasing the catalytic activity.
  • the diameter of the spherical structure is about 1.26 ⁇ m, and the size of the nanofiber is 10 to 12 nm.
  • the specific surface area was 191.56 m 2 /g, the average pore diameter was 1.95 nm, and the pore volume was 0.12 cm 3 /g.
  • the prepared manganese oxide material is subjected to drying and moisture removal to carry out a catalytic performance test:
  • a solution containing 10.53 parts of KMnO 4 was added to a solution of 24 parts of MnSO 4 ⁇ H 2 O, the temperature was controlled to 60 ° C, the pH was adjusted to 12 with potassium carbonate, and the reaction was stirred for 3 hours.
  • the SO 4 2- concentration was adjusted to about 1 mol/L, and stirred at 45 ° C for 3 h.
  • a solution of CuSO 4 , LaCl 3 , and Co(NO 3 ) 2 was added to stir, and the pH was adjusted to 7-8.
  • the filter is dried by washing and dried to obtain a manganese oxide material.
  • T Mn was 34.82%
  • K content was 0.49%
  • La content was 33.44%
  • Co content was 0.112%
  • Cu content was 4.05%.
  • the molar ratio of other metal elements such as K, La, Co, Cu to manganese is 0.5.
  • Y(Mn 2+ )/Y(Mn 4+ ) 0.08 was measured.
  • the chemical expression is K 0.019 La 0.38 Co 0.003 Cu 0.099 Mn 2+ 0.075 Mn 4+ 0.925 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, causing most of the Mn 2+ to enter the interior, resulting in doping of divalent manganese, forming A stable phase with a specific structure causes a large number of new defects to be generated inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution. At the same time, in order to maintain the structure of manganese dioxide after the lattice oxygen escapes, the adsorbed oxygen is converted into lattice oxygen. Thereby, the oxygen escaping ability and reversibility are increased, so that the manganese oxide material exhibits better catalytic activity.
  • the water absorption of the manganese oxide material was determined to be 8%.
  • the main phase structure was weak crystal ⁇ -MnO 2 (JCPDS No. 44-0141), and no characteristic peak of Mn 2 O 3 or Mn 3 O 4 was observed, and the heat stable temperature was 630 °C.
  • XRD results showed no significant peaks of rare earth, cobalt and other oxides and divalent manganese compounds.
  • divalent manganese is mainly present inside the manganese oxide material. Heating to 630 ° C failed to measure the decomposition of MnO 2 .
  • the skeleton structure of the manganese oxide material prepared in this embodiment is a manganese dioxide structure in which various elements including divalent manganese are doped to form a solid solution. Due to the doping of various elements, especially the doping of divalent manganese, the type of oxygen (such as lattice oxygen, adsorbed oxygen, etc.) is increased, the escape ability of lattice oxygen is improved, and various forms of oxygen are converted. The reversibility reduces the activation energy of the reaction, thereby increasing the catalytic activity of the manganese oxide material.
  • the size of the spherical structure is 1.28 to 1.45 ⁇ m, and the size of the nanofiber is 38 to 50 nm.
  • the specific surface area was 138.84 m 2 /g, the average pore diameter was 3.10 nm, and the pore volume was 0.21 cm 3 /g.
  • Lattice oxygen / adsorbed oxygen 2.4.
  • the prepared manganese oxide material was tested for catalytic performance:
  • Test A 50 g of the manganese oxide material was placed in a fixed bed reactor of 30 mm in diameter, and a mixed gas of 250 ppm CO, 1 ppm HCHO, and 1 ppm O3 was carried by dry air. The concentration of CO, HCHO and O 3 at the outlet was continuously detected at room temperature under the condition of GHSV 5000h -1 for 1 h. The conversion of CO was 95%, the conversion of HCHO was 100%, and the conversion of O 3 was 100%.
  • Test B The manganese oxide material prepared in the present embodiment is used as a catalyst for preparing monocyanamide from urea, and the urea conversion rate can reach more than 28%.
  • Test C The manganese oxide material obtained in the present example was subjected to a liquid VOCs adsorption decomposition test according to the method described in Test C of Example 1, and the measurement results are shown in Table 8.
  • Test D The prepared manganese oxide material was subjected to a wastewater treatment test:
  • Comparative test Mix 250 mL (COD 180 mg/L) wastewater and 1 g manganese oxide material. Under stirring conditions, take the supernatant to determine the residual COD after a period of time. The test results are shown in Table 9.
  • the manganese oxide material prepared in this embodiment can treat both gaseous organic pollutants and organic pollutants in liquids. After recycling, it can be reused after simple treatment, which is economical and environmentally friendly.
  • T Mn was 68.85% (dry basis) and moisture was 58.45%.
  • Y(Mn 2+ )/Y(Mn 4+ ) 0.80 was measured, and the chemical expression was Mn 2+ 0.445 Mn 4+ 0.555 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, causing most of the Mn 2+ to enter the interior, resulting in doping of divalent manganese, forming A stable phase with a specific structure causes a large number of new defects to be generated inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution. At the same time, in order to maintain the structure of manganese dioxide after the lattice oxygen escapes, the adsorbed oxygen is converted into lattice oxygen. Thereby, the oxygen escaping ability and reversibility are increased, so that the manganese oxide material exhibits better catalytic activity.
  • the water absorption of the manganese oxide material was measured to be 1%.
  • the main phase structure of the material detected by XRD was amorphous manganese dioxide, and no characteristic peak of Mn 2 O 3 or Mn 3 O 4 was observed, and the heat stable temperature was 500 °C.
  • the XRD results showed no significant characteristic peaks of the divalent manganese compound.
  • the type of oxygen (such as lattice oxygen, adsorbed oxygen, etc.) is increased, the escape ability of lattice oxygen and the reversibility of various forms of oxygen interconversion are increased, and the activation energy of the reaction is lowered. , thereby increasing the catalytic activity.
  • the microscopic features are irregular fibers or sheets composed of 1.36 to 2.15 ⁇ m ellipsoids.
  • the specific surface area was 213.56 m 2 /g, the average pore diameter was 5.21 nm, and the pore volume was 0.36 cm 3 /g.
  • Lattice oxygen / adsorbed oxygen 3.
  • the manganese oxide material prepared by washing and filtering in the present example was directly subjected to a heavy metal adsorption test according to the method described in the test B of Example 1, and the measurement results are shown in Table 10.
  • TMn was 55%
  • K content was 2.48%
  • Pr content was 0.8%
  • Ce content was 1.63%
  • Cu content was 2.62%.
  • High-value rare earth elements are low in content, high in resource utilization, and low in cost.
  • the molar ratio of other metal elements such as K, Pr, Ce, Cu to manganese is 0.12.
  • Y(Mn 2+ )/Y(Mn 4+ ) 0.32 was measured.
  • the chemical expression is K 0.063 Pr 0.005 Ce 0.012 Cu 0.04 Mn 2+ 0.245 Mn 4+ 0.755 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • a part of Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, causing most of the Mn 2+ to enter the interior, resulting in doping of divalent manganese, forming A stable phase with a specific structure causes a large number of new defects to be generated inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution.
  • the adsorbed oxygen is converted into lattice oxygen.
  • the oxygen escaping ability and reversibility are increased, so that the manganese oxide material exhibits better catalytic activity.
  • the manganese oxide material has a water absorption of 18%.
  • the hydrophobicity is good, so that the manganese oxide material has high catalytic activity and long service life under the condition of high humidity at room temperature, and can effectively remove harmful substances such as CO, VOCs and O 3 at the same time, and exhibits excellent moisture resistance and catalytic ability.
  • the micromorphology is characterized by an ellipsoid of 0.8-1.13 ⁇ m in diameter composed of nanofibers having a diameter of 12 to 21 nm.
  • the specific surface area was 175.34 m 2 /g, the average pore diameter was 4.13 nm, and the pore volume was 0.34 cm 3 /g.
  • Lattice oxygen / adsorbed oxygen 1.5.
  • the main phase of the manganese oxide material was ⁇ -MnO 2 (JCPDS No. 44-0141) by XRD.
  • the diffraction peaks in the spectrum were conspicuous and coincided with the characteristic peak of ⁇ -MnO 2 (JCPDS No. 44-0141), and no characteristic peak of Mn 2 O 3 or Mn 3 O 4 was observed.
  • the heat stable temperature is 650 ° C, which has good thermal stability and is beneficial to the regeneration of materials.
  • XRD results showed no significant peaks of rare earth, copper and other oxides and divalent manganese compounds.
  • divalent manganese is mainly present inside the manganese oxide material. Heating to 650 ° C failed to measure MnO 2 decomposition.
  • the skeleton structure of the manganese oxide material prepared in this embodiment is a manganese dioxide structure in which various elements including divalent manganese are doped to form a solid solution. Due to the doping of various elements, especially the doping of Mn 2+ , the type of oxygen is increased, the escape ability of lattice oxygen and the reversibility of various forms of oxygen interconversion are improved, and the activation energy of the reaction is lowered. Thereby, the catalytic activity of the manganese oxide material is improved.
  • Example 1 of Publication No. WO 2012/167280 A1 gave MnOx.
  • 50g of MnOx was placed in a fixed-bed reactor with a diameter of 30mm, and it was passed through dry air carrying 250ppm CO, 1ppm HCHO, 1ppm O 3 .
  • GHSV 1500h -1 the outlet was continuously tested for 1h, each tested.
  • the average catalytic conversion rate of the catalyst was short-time inactivation of CO, 100% of HCHO, and 100% of O 3 .
  • the outlet was continuously tested for 1h, and the average conversion rate of each analyte was short-time inactivation of CO, 65% of HCHO and 100% of O 3 .
  • TMn 59.98%
  • K content was 2.68%
  • Mg content was 1.01%.
  • the molar ratio of other metal elements such as K and Mg to manganese is 0.1.
  • Y(Mn 2+ )/Y(Mn 4+ ) 0.36 was measured.
  • the expression is K 0.063 Mg 0.038 Mn 2+ 0.265 Mn 4+ 0.735 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, causing most of the Mn 2+ to enter the interior, resulting in doping of divalent manganese, forming A stable phase with a specific structure causes a large number of new defects to be generated inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution. At the same time, in order to maintain the structure of manganese dioxide after the lattice oxygen escapes, the adsorbed oxygen is converted into lattice oxygen.
  • the manganese oxide material has a water absorption of 10%.
  • Lattice oxygen / adsorbed oxygen 3, is conducive to the migration of oxygen.
  • the specific surface area was 75.48 m 2 /g.
  • the main phase structure of the manganese oxide material was weak crystal ⁇ -MnO 2 (JCPDS No. 44-0141) and the thermal stability temperature was 500 ° C.
  • the characteristic peak of Mn 2 O 3 or Mn 3 O 4 did not occur, and the characteristic peaks of the magnesium compound and the divalent manganese compound did not occur.
  • the skeleton structure is a manganese dioxide structure in which a plurality of elements including divalent manganese are doped to form a solid solution. Due to the doping of various elements, especially the doping of Mn 2+ , the type of oxygen is increased, the escape ability of lattice oxygen and the reversibility of various forms of oxygen interconversion are improved, and the activation energy of the reaction is lowered. Thereby, the catalytic activity of the manganese oxide material is improved.
  • TMn 48.85%
  • K content was 8.6%
  • Ca content was 9.2%.
  • the molar ratio of other metal elements such as K and Ca to manganese is 0.5.
  • the expression is K 0.248 Ca 0.259 Mn 2+ 0.05 Mn 4+ 0.95 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, causing most of the Mn 2+ to enter the interior, resulting in doping of divalent manganese, forming A stable phase with a specific structure causes a large number of new defects to be generated inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution. At the same time, in order to maintain the structure of manganese dioxide after the lattice oxygen escapes, the adsorbed oxygen is converted into lattice oxygen. Thereby, the oxygen escaping ability and reversibility are increased, so that the manganese oxide material exhibits better catalytic activity.
  • the manganese oxide material has a water absorption of 15%.
  • Lattice oxygen / adsorbed oxygen 2.1.
  • the specific surface area was 199.86 m 2 /g.
  • the main phase structure of the manganese oxide material was amorphous manganese dioxide, and no characteristic peak of Mn 2 O 3 or Mn 3 O 4 was observed by XRD.
  • the thermal stability temperature was 580 °C.
  • the XRD results showed no significant characteristic peaks of the divalent manganese compound.
  • the skeleton structure of the manganese oxide material prepared in this embodiment is an amorphous manganese dioxide structure. Due to the doping of various elements, especially the doping of Mn 2+ , the type of oxygen is increased, the escape ability of lattice oxygen and the reversibility of various forms of oxygen interconversion are improved, and the activation energy of the reaction is lowered. Thereby, the catalytic activity of the manganese oxide material is improved.
  • the exhaust gas purifying device includes a purifying member 3 and an inlet 1 on one side of the purifying member 3, and an outlet 6 on the other side of the purifying member 3.
  • the purification member 3 is provided with the manganese oxide material prepared in this embodiment.
  • a suspension of 169.3 parts of MnCO 3 was added, 157.6 parts of K 2 MnO 4 was added , the temperature was maintained at 50 ° C, adjusted to pH 8-12 with NaOH, and stirred for 4 h. Then, the SO 4 2- concentration was adjusted to about 1 mol/L with sulfuric acid, and stirred at 50 ° C for 2 h. After washing and filtration, CuSO 4 , LaCl 3 , and CeCl 3 were added , adjusted to pH 7-8, stirred for 2 hours, washed, filtered, and dried to obtain a manganese oxide material.
  • T Mn was 52.1%
  • K content was 2.18%
  • Na content was 3.90%
  • La content was 1.86%
  • Ce content was 2.72%
  • Cu content was 4.55%.
  • the molar ratio of other metal elements such as K, Na, La, Ce, Cu to manganese is 0.35.
  • Y(Mn 2+ )/Y(Mn 4+ ) 0.47 was measured.
  • the manganese oxide material prepared in this example has the expression K 0.06 Na 0.18 La 0.014 Ce 0.02 Cu 0.075 Mn 2+ 0.32 Mn 4+ 0.68 O 2 .
  • Mn 2+ is adsorbed by manganese dioxide, part of it is oxidized to Mn 4+ due to the surface self-catalysis, and the internal Mn 4+ is correspondingly reduced to Mn 2+ , thereby creating new defects inside.
  • a part of Mn 2+ diffuses into the crystal lattice to form a solid solution, causing new defects; or Mn 2+ replaces Mn 4+ on the crystal lattice, causing most of the Mn 2+ to enter the interior, resulting in doping of divalent manganese, forming A stable phase with a specific structure causes a large number of new defects to be generated inside. These defects make the lattice oxygen rich and reduce the activation energy of lattice oxygen evolution.
  • the adsorbed oxygen is converted into lattice oxygen.
  • the oxygen escaping ability and reversibility are increased, so that the manganese oxide material exhibits better catalytic activity.
  • the water absorption of the manganese oxide material was 7%.
  • the main phase structure was detected by XRD as weak crystal ⁇ -MnO 2 (JCPDS No.44-0141) and amorphous manganese oxide.
  • No characteristic peaks and rare earths of divalent manganese compounds, Mn 2 O 3 or Mn 3 O 4 were observed.
  • Characteristic peaks of compounds such as copper No characteristic peak of MnO, Mn 2 O 3 or Mn 3 O 4 was observed when heated to 560 ° C, and the heat stable temperature was 560 ° C.
  • the size of the spherical structure is 1.51 to 1.92 ⁇ m, and the size of the nanofiber is 31 to 40 nm.
  • the specific surface area was 186.7 m 2 /g, the average pore diameter was 6.54 nm, and the pore volume was 0.25 cm 3 /g.
  • Lattice oxygen / adsorbed oxygen 0.75.
  • the skeleton structure of the manganese oxide material prepared in this embodiment is a manganese dioxide structure in which a plurality of elements including divalent manganese are doped to form a solid solution, and divalent manganese is mainly present in the manganese oxide material. internal. Due to the doping of various elements, especially the doping of Mn 2+ , the type of oxygen (such as lattice oxygen, adsorbed oxygen, etc.) is increased, the escape ability of lattice oxygen is improved, and various forms of oxygen conversion are realized. The reversibility reduces the activation energy of the reaction, thereby increasing the catalytic activity of the manganese oxide material.
  • the inlet 1, the first filter member 2, the purification member 3, the rotary vane fan 4, the second filter member 5, the outlet 6, and the outer casing 7 are included.
  • the inlet 1 is located at the top of the air purifier with the opening facing upwards (the inlet 1 can also be front and/or side).
  • the first filter member 2, the purification member 3, the rotary vane fan 4, and the second filter member 5 are located inside the outer casing 7; from the top to the bottom, the inlet 1, the first filter member 2, the purification member 3, and the rotary vane fan 4.
  • the outlet 6 is located on the side of the bottom.
  • the inlet 1, the first filter member 2, the purification member 3, the second filter member 5, the blower 4, and the outlet 6 are sequentially arranged in the order in which the air flows.
  • the rotary vane fan 4 is driven by a motor, and a movable vane is installed between the shaft of the rotary vane fan 4 and the cavity shell, and the space enclosed by the shaft, the cavity shell and the movable vane when the rotary vane fan 4 rotates
  • the cyclic change takes in air and then discharges it.
  • the rotation direction of the rotary vane fan 4 is controlled by the control device (not shown), the air flow direction also changes, the original inlet 1 becomes the new outlet 1, and the original outlet 6 becomes the new inlet 6; at this time, the air flows.
  • the order is the new inlet 6, the second filter member 5, the rotary vane fan 4, the purification member 3, the first filter member 2, and the new outlet 1. It is also possible to provide only the first filter element 2 or the second filter element 5, or even to cancel all filter elements.
  • the air introduced by the rotary vane fan 4 is filtered and then contacted with the manganese oxide material in the purification member 3, dust and moisture can be reduced, and the life and efficiency of the manganese oxide material can be improved.
  • the inlet 1 of the larger air purifier When the inlet 1 of the larger air purifier is at the top and the outlet 6 is at a lower position, contaminants such as ozone, which are denser than air, are not easily sucked into the air purifier; the inlet 1 at a high place and the exit at a lower place 6 interchangeable, can improve the treatment rate of pollutants such as ozone with a higher density than air, and improve the efficiency of the air purifier. On the contrary, it can improve the treatment efficiency of pollutants such as smoke with a density lower than that of air.
  • the inlet 1 and the outlet 6 are alternately used interchangeably, and the dust attached to the first filter member 2, the second filter member 5, and the purification member 3 can be reduced or eliminated, the resistance is reduced, and the first filter member 2 and the second filter member 5 are extended. And the life of the purification component 3.
  • the manganese oxide materials prepared in Examples 1-5, and the manganese oxide materials prepared in Examples 6-10 were supported on an Al 2 O 3 carrier, respectively, including an inlet 1, a first filter member 2, and a purification member 3.
  • the purification unit 3 of the air cleaner of the rotary vane fan 4 the second filter unit 5 and the outlet 6.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Physics & Mathematics (AREA)
  • Organic Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Composite Materials (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Catalysts (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

L'invention porte sur un matériau à base d'oxyde de manganèse et sur un procédé pour la préparation de celui-ci, en ce qui concerne le domaine technique des matériaux catalytiques et de la protection de l'environnement. Le matériau à base d'oxyde de manganèse comprend du dioxyde de manganèse, la valence de l'élément manganèse comprenant du manganèse divalent et du manganèse tétravalent et le rapport du manganèse divalent au manganèse tétravalent étant de 0<Y(Mn2+)/Y(Mn4+)<1. Le matériau à base d'oxyde de manganèse a une structure sphérique constituée de nanobâtonnets et d'un passage poreux favorable. Le matériau à base d'oxyde de manganèse a une bonne stabilité thermique, une grande surface spécifique et de fortes capacités d'adsorption et d'échange d'ions pendant l'utilisation, il présente une activité catalytique élevée et une longue durée de vie dans des conditions d'humidité élevée et il permet d'éliminer efficacement des matières dangereuses telles que le CO, les COV et l'O3 (l'ozone) et de tuer les staphylocoques, etc. soit individuellement, soit simultanément. Le procédé pour la préparation du matériau à base d'oxyde de manganèse est respectueux de l'environnement, simple, pratique, largement disponible, à faible coût et facile à mettre en œuvre à une échelle industrielle.
PCT/CN2018/072207 2017-08-12 2018-01-11 Matériau à base d'oxyde de manganèse et procédé pour la préparation de celui-ci Ceased WO2019033695A1 (fr)

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