WO2019033695A1 - Manganese oxide material and method for preparing same - Google Patents

Abstract

A manganese oxide material and a method for preparing same, relating to the technical field of catalytic materials and environmental protection. The manganese oxide material comprises manganese dioxide, wherein the valence form of the manganese element comprises divalent manganese and tetravalent manganese, and the ratio of the divalent manganese to the tetravalent manganese is 0<Y(Mn2+)/Y(Mn4+)<1. The manganese oxide material has a spherical structure consisting of nanorods and a favorable pore passage. The manganese oxide material has good thermal stability, large specific surface area, and strong adsorption and ion exchange capabilities during use, features high catalytic activity and long service life under a high humidity condition, and can efficiently remove hazardous materials such as CO, VOCs, and O3 (ozone) and kill staphylococcus, etc. either alone or simultaneously. The method for preparing a manganese oxide material is environment-friendly, simple, practicable, extensively available, low in cost, and easy to implement industrialization.

Description

Manganese oxide material and preparation method thereof Technical field

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.

Background technique

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. At present, 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.

With the improvement of people's living standards, transportation, room decoration, printing technology development and use, the resulting CO, VOCs, O ₃ also caused more different concentrations and types of waste gas, wastewater, etc. in our living environment. Pollution. For example, ozone generated by copier toner heating and organic exhaust gas, ozone generated by ultraviolet lamp sterilization is a strong carcinogen.

At present, 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. Among them, 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.

As early as 1919, Johns Hopkins University and the University of California jointly developed a Hogarat catalyst made from manganese dioxide and copper oxide in a certain ratio for the elimination of CO and VOCs at low temperatures. However, it is inactivated by water or water vapor. Although after years of development, the copper-manganese oxide is modified by doping other elements to improve its hydrothermal stability, heat resistance and low-temperature activity to improve the efficiency of different catalytic reactions. However, at present, the main commercial catalysts still have large problems in terms of hydrothermal stability, especially in the high humidity conditions in the south, the service life and effects are greatly affected.

The Chinese Patent Application Publication No. CN103506111A, published on January 15, 2014, 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.

The preparation of a novel Mn-based metal oxide (MnOx) catalyst and its application in the field of low-temperature catalytic combustion of volatile organic compounds (VOCs) is disclosed in Chinese Patent Application Publication No. CN105921146A. application. 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.

The PCT International Patent Application Publication No. WO 2012/167280 A1, issued on Dec. 6, 2012, 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. Organic compounds (VOC) and ozone. 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. In some specific inventions, 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.

These prior art technologies have poor performance under high humidity conditions, and cannot simultaneously remove common CO, VOCs, O ₃ and other pollutants in the indoor environment. The raw materials are expensive, the preparation method is complicated, industrialization is difficult, activity is low, and efficiency is low. , short life, unstable, difficult to regenerate, easy to absorb moisture and other defects.

Summary of the invention

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 α-MnO ₂ and/or amorphous manganese dioxide.

In one preferred embodiment of the present invention, the crystalline structure of the manganese oxide material comprises weakly crystalline α-MnO ₂ and/or amorphous manganese dioxide.

According to still another preferred embodiment of the present invention, 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, and the Y(Mn ⁴⁺ ) is a mass fraction of the tetravalent manganese in the manganese oxide material. Preferably, 0.08 ≤ Y(Mn ²⁺ )/Y(Mn ⁴⁺ )<1. More preferably, Y(Mn ²⁺ )/Y(Mn ⁴⁺ )=0.1-0.8. Most preferably, Y(Mn ²⁺ )/Y(Mn ⁴⁺ ) = 0.36-0.8.

According to still another preferred embodiment of the present invention, 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. Preferably, the T _Mn is from 34.82 to 55.45 wt%.

According to still another preferred embodiment of the present invention, the manganese dioxide comprises a weak crystalline α-MnO ₂ .

According to still another preferred embodiment of the present invention, the card number of the weak crystal α-MnO ₂ detected by XRD is JCPDS No. 44-0141.

According to still another preferred embodiment of the present invention, the weak crystal α-MnO ₂ and/or the amorphous manganese oxide in the manganese oxide material gradually tends to α-MnO ₂ as the temperature increases.

The present invention still further preferred aspect, the weak crystalline α-MnO ₂ and / or amorphous manganese oxide can then transition to the α-MnO ₂ into weakly crystalline α-MnO ₂ and / or amorphous manganese oxide .

According to still another preferred embodiment of the present invention, the manganese oxide material has a heat stable temperature of >535 °C. Preferably, the heat stable temperature is ≥ 540 °C.

According to still another preferred embodiment of the present invention, the manganese oxide material has a heat stable temperature of ≤600 °C.

According to still another preferred embodiment of the present invention, 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.

According to still another preferred embodiment of the present invention, 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 . Wherein A is a metal element of the main group, and 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.

According to still another preferred embodiment of the present invention, 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.

According to still another preferred embodiment of the present invention, 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.

According to still another preferred embodiment of the present invention, the spherical structure has a diameter of 0.9 to 2.2 μm. The nanofiber rod has a diameter of 10 to 50 nm. Preferably, the spherical structure has a diameter of 0.9 to 1.92 μm. More preferably, the spherical structure has a diameter of 0.9 to 1.55 μm. Preferably, the nanofiber rod has a diameter of 10 to 42 nm. More preferably, the nanofiber rod has a diameter of 15 to 26 nm.

According to still another preferred embodiment of the present invention, 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.

According to still another preferred embodiment of the present invention, the oxygen in the manganese oxide material includes lattice oxygen and adsorbed oxygen, and the lattice oxygen/adsorbed oxygen=(1 to 3):1. Preferably, the lattice oxygen/adsorbed oxygen is 1.5.

According to still another preferred technical solution of the present invention, the α-MnO ₂ skeleton structure, the 16-26 nm diameter nanofiber rod has a spherical structure with a diameter of 1.09 to 1.55 μm; the main phase of the manganese dioxide is a weak crystal α-MnO ₂ and amorphous The manganese oxide, the weak crystal α-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, and the transition metal is preferably at least one of Cu, Co, Ag, and rare earth, and 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.

According to still another preferred embodiment of the method for producing a manganese oxide material of the present invention, 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.

According to a preferred embodiment of the method for preparing a manganese oxide material of the present invention, 202.8 parts of MnSO ₄ ·H ₂ O solution is adjusted with NaOH and maintained at pH 12 or higher, 126.4 parts of KMnO 4 is added, and the temperature is maintained at 50 ° C, and stirred. Obtaining a suspension; then adding 142.2 parts of MnSO ₄ ·H ₂ O, controlling pH 8-9, stirring at 50 ° C; then adjusting the concentration of SO ₄ ^2- to about 1 mol/L with sulfuric acid, stirring at 50 ° C; washing and filtering CuSO ₄ , LaCl ₃ , and CeCl ₃ were added to the insoluble matter, adjusted to pH 7-8, stirred, washed, filtered, and dried to obtain a manganese oxide material.

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. 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.

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.

According to still another preferred embodiment of the air purifying device of the present invention, a filter member is disposed between the inlet 1 and/or the outlet 6 and the purification member 3.

According to still another preferred embodiment of the present invention, the inlet 1 is located at the top.

According to still another preferred embodiment of the present invention, the inlet 1 is located on the front side and/or the side.

According to still another preferred embodiment of the present invention, the outlet 6 is located at the bottom.

According to still another preferred embodiment of the air purifying device of the present invention, 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.

The invention has the following advantages:

1) 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.

2) Larger than the surface, good pores, good molecular adsorption. Oxygen exists in many forms to facilitate the migration of oxygen.

3) High catalytic activity and long service life under high temperature and room temperature conditions, and can effectively remove harmful substances such as CO, VOCs and O ₃ separately or simultaneously, and can also kill bacteria. It exhibits excellent moisture resistance and catalytic ability and is suitable for use in bacteria-prone environments. Has important social significance and extensive commercial application value. It works better under heating conditions.

4) A spherical structure composed of nanorods, small and uniform in size, good in dispersion and high in activity. 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.

5) It can fully utilize rare earth elements such as lanthanum and cerium, and expand the application field of rare earths, which is beneficial to the balanced utilization of rare earths.

6) The ratio of copper to manganese and the mass percentage of rare earth elements are lower than those of the prior art, and the relative resource utilization rate is high and the cost is lower.

7) 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.

8) It can treat organic pollutants in gases as well as organic pollutants and heavy metal pollutants in water. After recycling, it can be used several times with simple treatment, which is economical and environmentally friendly.

9) Strong adsorption and ion exchange capacity, can exchange with a variety of metal elements. Can handle heavy metal ion contaminants.

10) The preparation method of the invention is environmentally friendly and simple, and has a wide range of raw materials, low cost, and easy industrialization.

11) 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.

DRAWINGS

1 is an X-ray diffraction (XRD) pattern of a manganese oxide material prepared in Example 1. Wherein A is dried at 50 ° C for 24 h; B is calcined at 500 ° C for 2 h; C is calcined at 550 ° C for 2 h; D is calcined at 600 ° C for 2 h; E is calcined at 700 ° C for 2 h; F at 800 ° C The mixture was calcined for 2 hours; G was calcined at 600 ° C for 2 h and then used at room temperature for 1 year.

2 is an 8K-fold magnified SEM image of the manganese oxide material prepared in Example 1.

3 is a 50K-fold enlarged SEM image of the manganese oxide material prepared in Example 1.

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).

8 is an XRD pattern of the manganese oxide material I prepared in Example 2, wherein 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.

9 is an XRD pattern of the manganese oxide material II prepared in Example 2, wherein 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.

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.

Detailed ways

In the process of preparing the manganese oxide material of the present invention, the following series of complicated chemical reactions occur:

Oxidation method: Mn ²⁺ + oxidant → MnO ₂ + reduction product (a)

Reduction method: MnO ^4- + reducing agent → MnO ₂ + oxidation product (b)

MnO ₄ ^- + organic → MnO ₂ + oxidation product (b1)

Redox method: 3Mn ²⁺ +2MnO ₄ ^- +2H ₂ O→5MnO ₂ +4H ⁺ (c)

Mn ²⁺ +MnO ₄ ^2- →2MnO ₂ (c1)

Under alkaline conditions (MnO _{2 is the} most stable):

Mn(OH) _{3 is} prone to disproportionation: Mn(OH) ₃ →Mn(OH) ₂ +MnO ₂ (d)

Under acidic conditions (Mn ^{2+ is the} most stable):

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)

In the process of preparing the manganese oxide material of the invention, Mn ³⁺ is disproportionated, and most of the manganese element exists in the form of divalent manganese and tetravalent manganese, and the trivalent manganese is negligible. That is, TMn=Y(Mn ²⁺ )+Y(Mn ⁴⁺ ).

The adsorption of 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. In the 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 invention is further illustrated by the following specific examples.

Example 1

See Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7. 202.8 parts by weight of MnSO ₄ ·H ₂ O was dissolved in deionized water, 126.4 parts of KMnO _{4 was} added, adjusted with NaOH and maintained at pH 12 or higher, kept at a temperature of 50 ° C, and stirred for 2 hours. Then, 142.2 parts of MnSO ₄ ·H 2 O was added, pH 8-9 was controlled, and the mixture was stirred at a temperature of 50 ° C for 2 hours to obtain a precipitate A. Then, the concentration of SO ₄ ^{2- was} adjusted to about 1 mol/L with sulfuric acid, and stirred at 50 ° C for 2 hours to obtain precipitate B. After washing and filtration, CuSO ₄ , LaCl ₃ , and CeCl _{3 were added} to adjust to pH 7-8, and the mixture was stirred for 2 hours to obtain precipitate C. After washing and filtering, drying was carried out to obtain a manganese oxide material.

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.

It can be seen from Table 1 that in addition to Na, most of the metal elements such as K, La, Ce, and Cu are located inside the material (such as in the skeleton and/or in the pores), rather than being present on the surface in the form of adsorption or the like.

Table 1

Y(Mn ²⁺ )/Y(Mn ⁴⁺ )=0.48 was measured. 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 . 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. Or a portion of 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. 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. After doping with rare earth and copper elements, the active sites and vacancy defects are further increased to exhibit superior catalytic activity.

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). ).

Using Ultima-IV XRD diffractometer, Cu-Kα ray is selected, the scanning range is 5～80°, the working voltage is 40KV, the working current is 40mA, and the scanning speed is 0.03°/s (the same below). The main phase is weak crystal α-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 α-MnO ₂ . In the range of 50-550 ° C, 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. With the increase of temperature, the dispersion peak gradually weakens and the characteristic peak of α-MnO ₂ gradually becomes stronger, indicating that the crystal phase structure gradually changes to α-MnO ₂ with increasing temperature. After 600 °C, 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. And 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.

In general, 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 ℃ 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 analysis of the detection results of XRD and the like shows that 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.

Scanning electron microscopy (SEM) manganese oxide material is a spherical structure with a large number of 16~26nm nanofiber rods with a diameter of 1.09~1.55μm. 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 specific surface area was measured to be 257.33 m ² /g, the average pore diameter was 5.93 nm, and the pore volume was 0.40 cm ³ /g. After XPS analysis, lattice oxygen/adsorbed oxygen = 1.5.

In summary, the manganese oxide material prepared in this embodiment has a structure of α-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. At +3 price. 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.

The performance of manganese oxide materials is determined by various tests as follows:

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:

Table 2

Test B. The obtained manganese oxide material was subjected to heavy metal adsorption test after drying to remove water:

15 mL of Pb ²⁺ , Cu ²⁺ , Cd ²⁺ , Co ²⁺ , Zn ²⁺ solutions with a concentration of 4.5 mmol and 1 mmol/l, respectively, with a manganese oxide material with a pH of 4.5 and a concentration of 20 mg/mL. 1 ml of the suspension was shake-mixed at room temperature for 2 h, and the remaining concentration of each heavy metal ion in the supernatant was measured. The adsorption of Pb ²⁺ , Cu ²⁺ , Cd ²⁺ , Co ²⁺ and Zn ²⁺ by manganese oxide materials was calculated. The results of the adsorption amount measurement are shown in Table 3.

It can be seen from Table 3 that 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.

table 3

heavy metal ion	Pb 2+	Cu 2+	Cd 2+	Co 2+	Zn 2+
Adsorption amount (mmol/kg)	280	110	100	90	95

Test C. The prepared manganese oxide material is subjected to drying and removing water, and then subjected to liquid VOCs adsorption decomposition test:

After adding 1 g of manganese oxide material in 2000 mL of toluene aqueous solution (toluene concentration: 0.1 g/L), the concentration of remaining toluene in the supernatant was measured, and the concentration of toluene in the supernatant was measured according to the change in concentration of toluene. Adsorption capacity. The manganese oxide material to which toluene was adsorbed was packed in a fixed bed reactor, and was purged with hot air at a temperature of 350 ° C at GHSV 5000 h ^-1 to measure the concentrations of toluene, CO ₂ and CO at the outlet.

The purged manganese oxide material was further circulated for toluene adsorption and decomposition tests, and the test results are shown in Table 4.

Table 4

It can be seen from Table 3 and Table 4 that 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 α-MnO ₂ and amorphous manganese dioxide after calcination at 550 ° C for 2 h; the dispersion peak is weaker and the α-MnO ₂ characteristic peak is more obvious than the normal temperature drying. Part of the amorphous state is converted to α-MnO ₂ . After about 1 year, 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 α-MnO ₂ in the manganese oxide material is converted into weak crystal α-MnO ₂ and non- Crystalline manganese dioxide.

Test E. The prepared manganese oxide material was subjected to wastewater COD treatment and comparative test:

250 mL (180 mg/L of COD) wastewater was stirred with 1 g of manganese oxide material or activated carbon, and thoroughly mixed. Tested separately by air or no air, and the supernatant is taken for a period of time to determine the remaining COD. The test results are shown in Table 5. It can be seen from Table 5 that the manganese oxide material has a significant catalytic effect on the wastewater COD when the air is introduced.

table 5

It can be seen from Test D, Test E and Table 5 that the manganese oxide material together with the air can effectively reduce the indoor formaldehyde content or the wastewater COD.

In summary, 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.

Example 2

See Figure 8, Figure 9, Figure 11.

190.4 parts of MnCl _{2 was} dissolved, and 54.2 parts of sodium chlorate was added while stirring at 45 ° C while maintaining the pH to 3 to 5. The pH was adjusted to 7 with potassium carbonate, and then 135.2 parts of MnSO ₄ ·H ₂ O was added, and the mixture was stirred at a temperature of 40 ° C for 2.5 hours to obtain a precipitate B. The precipitate B was washed, filtered, and dried to obtain a manganese oxide material I. The precipitate was washed and filtered, and then added with a CuSO ₄ solution, stirred, and adjusted to pH 8 to 9 with NaOH. After 2 hours, the mixture was washed, filtered, and dried to obtain a manganese oxide material II.

The content of each metal element of manganese oxide materials I and II by ICP is shown in Table 6. When the copper element is doped, 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. 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. Or 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. There is a large amount of divalent manganese in the manganese dioxide, which produces divalent manganese doping, forming a stable solid solution, which causes a lot 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 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 μm 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 μm 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.

Table 6

It can be seen from Table 6 that 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 α-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.

In FIG. 8, the pattern B for the weak grain α-MnO _2; with respect to the pattern A, a pattern B, α-MnO ₂ peaks more apparent, occurs partially crystalline α-MnO ₂ weak transition to the α-MnO _2. 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 α-MnO ₂ after long-term use can be converted into the weak crystal α-MnO ₂ .

In Fig. 9, the spectrum B is a weak crystal α-MnO ₂ ; with respect to the spectrum A, the characteristic peak of the α-MnO ₂ in the spectrum B is more pronounced, and a partial transition to α-MnO ₂ occurs. Map D is similar to map A. The diffraction peak around 36° disappears in map D, indicating that the transformed α-MnO ₂ can be converted into weak crystal α-MnO ₂ .

Comparing Fig. 8 and Fig. 9, there is no significant difference, indicating that the phase structure of the material does not change after Cu is doped. From Table 6 and Test A, the results of the comparative test show that Cu replaces part of K in manganese oxide material II, which increases the type of doping element and improves the catalytic performance.

In summary, 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 α-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.

According to the analysis of the XRD test results, 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%.

It is indicated that manganese oxide material I has good catalytic activity. However, 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.

Comparative test: potassium hydroxide, sodium hydroxide, manganese monoxide and manganese dioxide molar ratio M (K): M (Na): M (Mn ²⁺ ): M (Mn ^{4 +} ) = 0.125: 0.265: Mix 0.155:0.845 and dry to obtain mixture I.

Potassium hydroxide, sodium hydroxide, copper sulfate, manganese monoxide and manganese dioxide molar ratio M (K): M (Na): M (Cu): M (Mn ²⁺ ): M (Mn ^{4 +} ) =0.085:0.265:0.03:0.155:0.845, mix and dry to obtain a mixture II.

When the mixture I and II were heated to 540 ° C by XRD, the characteristic peak of Mn ₂ O ₃ appeared.

50 g of the mixtures I and II were respectively tested in accordance with Test A of this example. It was found that the CO content of the mixture I flowing out at the beginning of the test decreased, but the CO content in the mixed gas flowing out after a short time was restored to 250 ppm and no longer decreased.

It was found that the CO content of the mixture II flowing out at the beginning of the test was more pronounced than that of the measured mixture I, but the CO content in the mixed gas which flowed out after a short time was restored to 250 ppm and no longer decreased.

It can be seen from the comparison test that the mixture I and the manganese oxide material I, the mixture II and the manganese oxide material II have the same chemical composition, but the performance differs greatly, reflecting that the structure is indistinguishable from the manganese oxide material.

Example 3

See Figure 10, Figure 12.

336.4 parts of MnCl _{2 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.

After testing, the T _Mn was 68.37%. Y(Mn ²⁺ )/Y(Mn ⁴⁺ )=0.69 was measured. 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. Or 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, 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 μm, 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. In the range of 50-400 °C, 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; When 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. After 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.

In summary, Mn ^{2+ is} mainly present inside the manganese oxide material. Heating to 500 ° CMn ₃ O ₄ characteristic peaks are obvious.

It can be seen from the analysis of the XRD detection results that 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.

Test A. The prepared manganese oxide material was tableted and subjected to a catalytic performance test.

50 g of manganese oxide material was placed in a 30 mm diameter fixed bed reactor, and 250 ppm CO carried by dry air was passed through, and the outlet CO concentration was continuously tracked for 1 h under the conditions of a reaction temperature of 85 ° C and a GHSV of 5000 h ^-1 . The conversion rate of CO is 100%.

4g of manganese oxide material was placed in a fixed-bed reactor with a diameter of 14mm, and 10ppmHCHO carried by air with a relative humidity of 95% was introduced, and the outlet was continuously detected under the conditions of a reaction temperature of 15 to 35 ° C and a GHSV of 40000 h ^-1 . HCHO concentration was 2 h. The conversion rate of HCHO was 80%.

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.

Table 7

heavy metal ion	Pb 2+	Cu 2+	Cd 2+	Co 2+	Zn 2+
Adsorption amount (mmol/kg)	98	165	50	20	45

Example 4

An ice-cold 30 wt% aqueous solution of ethanol was slowly added to a freshly prepared mixture containing about 15 parts of NH ₄ MnO ₄ and NH ₃ ·H ₂ O, and reacted at -10 to 0 ° C until the purple color disappeared. Thereafter, the mixture was mixed with 4.1 parts of MnCl _{2 to} maintain the pH of the system at 9.5, and stirred at room temperature. The solution was then adjusted to have a Cl ^- concentration of about 0.13 mol/L with ammonium chloride and stirred at room temperature for 3 h. After washing and filtering, CeCl ₃ was added to stir evenly, and the pH was adjusted to 9-10, and stirred for 2 hours. The manganese oxide material is obtained by washing and filtering.

After testing, 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.

Y(Mn ²⁺ )/Y(Mn ⁴⁺ )=0.11 was measured. The chemical expression is Ce _0.67 Mn ²⁺ _0.1 Mn ⁴⁺ _0.9 O ₂ . 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. Or 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. 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.

Among the micromorphological features of the manganese oxide material, the diameter of the spherical structure is about 1.26 μm, 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 nanofiber has small size, good dispersion and high activity. After XPS detection and analysis, lattice oxygen / adsorption oxygen = 1, to facilitate the migration of oxygen.

The prepared manganese oxide material is subjected to drying and moisture removal to carry out a catalytic performance test:

5 g of manganese oxide material was placed in a 14 mm diameter fixed bed reactor, and 10 ppm of NO carried by dry air was introduced. The NO concentration of the outlet was continuously tracked for 1 h under the conditions of a reaction temperature of 35 ° C and a GHSV of 5000 h ^-1 . The conversion rate of NO was 56%.

4 g of manganese oxide material was placed in a fixed bed reactor of 14 mm in diameter, and 10 ppm HCHO carried by air having a relative humidity of 95% was passed, and the outlet HCHO concentration was continuously detected at room temperature under a GHSV of 40000 h ^-1 for 1 h. The conversion rate of HCHO is 100%.

Example 5

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. After washing and filtering, 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.

After analysis, T _Mn was 34.82%, K content was 0.49%, La content was 33.44%, Co content was 0.112%, and 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 . 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. Or 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. 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 α-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.

In summary, divalent manganese is mainly present inside the manganese oxide material. Heating to 630 ° C failed to measure the decomposition of MnO ₂ .

The analysis of the XRD detection results shows that 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 μm, 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.

Table 8

Test D. The prepared manganese oxide material was subjected to a wastewater treatment test:

The mixture was thoroughly mixed with 250 mL (COD of 180 mg/L) wastewater and 1 g of manganese oxide material, and air was introduced under stirring. After a period of time, the supernatant was taken to determine the remaining COD. The test results are shown in Table 9.

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.

Table 9

It can be seen from the above that 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.

Example 6

21.5 parts of fresh MnCO ₃ was added dropwise with an aqueous solution of hydrogen peroxide at 65 ° C under a pH of 11 to substantially no foam generation. 25.4 parts of MnSO ₄ ·H ₂ O was added while stirring to maintain the pH of the system at 8, and the temperature was 80 °C. Nitric acid was then used to adjust the NO ₃ ^- concentration to about 0.32 mol/L, and the temperature was controlled to stir at 80 ° C for 30 min. The manganese oxide material is obtained by washing and filtering.

After testing, 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 . 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. Or 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. 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.

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 microscopic features are irregular fibers or sheets composed of 1.36 to 2.15 μm 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.

4 g of manganese oxide material was placed in a fixed bed reactor of 14 mm in diameter, and ¹ ppm HCHO carried by air having a relative humidity of 55% was passed, and the outlet HCHO concentration was continuously detected at room temperature under a condition of GHSV 3600 h ^-1 for 1 h. The conversion rate of HCHO is 100%.

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.

Table 10

heavy metal ion	Pb 2+	Cu 2+	Cd 2+	Co 2+	Zn 2+
Adsorption amount (mmol/kg)	191	69	59	65	48

Example 7

See Figure 13, Figure 14. After stirring 29.41 parts of Mn(AC) ₂ ·4H ₂ O, 12.64 parts of KMnO ₄ was added, and the reaction was stirred at a temperature of 50 ° C for 2 hours under conditions of KOH adjusting [OH] ^- to 1 mol/L. Then, 10.9 parts of MnSO ₄ ·H ₂ O was added to maintain the pH of the system at 10, and the mixture was stirred at 45 ° C for 3 h. It was then adjusted with sulfuric acid and potassium chloride to a concentration of SO ₄ ^{2- of} about 0.8 mol/L, a Cl ^- concentration of about 0.13 mol/L, and stirred at 60 ° C for 1 h. After filtration and washing with stirring is added _{CuSO 4, PrCl 3, CeCl 3} , the pH was adjusted stirred at 8 ~ 9 2h. The filter is dried by washing and dried to obtain a manganese oxide material.

After testing, TMn was 55%, K content was 2.48%, Pr content was 0.8%, Ce content was 1.63%, and 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 . 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. Or 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. 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 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 μm 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 α-MnO ₂ (JCPDS No. 44-0141) by XRD. The diffraction peaks in the spectrum were conspicuous and coincided with the characteristic peak of α-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.

In summary, divalent manganese is mainly present inside the manganese oxide material. Heating to 650 ° C failed to measure MnO ₂ decomposition.

The analysis of the XRD detection results shows that 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.

50g of manganese oxide material 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 , and continuously tested for 1h at room temperature and GHSV 1500h ^-1 . , no CO, HCHO, O ₃ . The catalytic conversion rates of CO, HCHO and O ₃ were both 100%. Under the condition of GHSV 5000h ^-1 , the outlet was continuously tested for 1 h, and the average conversion rates of the measured substances were CO 82%, HCHO 83%, and O ₃ 100%, respectively.

Comparative example

The preparation method described in 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 . At room temperature, 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 . Under the condition of GHSV 5000h ^-1 , 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 .

Example 8

Dissolve 19.6 parts of Mn(AC) ₂ ·4H ₂ O and 3.42 parts of Mg(A C) ₂ ·4H ₂ O, and add 8.42 parts of KMnO ₄ while stirring, and adjust the condition of [OH ^- ] to 2 mol/L with KOH at a temperature of 60 ° C. The reaction was stirred for 2 h. Then 16.29 parts of MnCl 2 was added to maintain the system pH ≥ 12 and the temperature was 75 ° C and stirred for 45 min. The Cl ^- concentration was controlled at about 2.3 mol/L and stirred for 2 h. The filter is dried by washing and dried to obtain a manganese oxide material.

After testing, TMn was 59.98%, K content was 2.68%, and 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 . 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. Or 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. 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 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 α-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.

50g of manganese oxide material 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 , and continuously tested for CO and HCHO at room temperature and GHSV 5000h ^-1 . , O ₃ concentration 1h. The catalytic conversion of CO is 65%, the catalytic conversion of HCHO is 81%, and the catalytic conversion of O ₃ is 85%.

Example 9

See Figure 15.

10 parts of KMnO _{4 was} dissolved in water, and an appropriate amount of wastewater with a COD of about 1000 mg/L after neutralization with lime was added under stirring to adjust the pH to 7-8, and the reaction was allowed to stand at room temperature for 1.5 h until the magenta disappeared. Further, an appropriate amount of wastewater containing Mn ²⁺ was added, and the pH was maintained at 7 to 8, and stirred at room temperature for 1 hour. After filtration and washing, the concentration of Cl ^- was adjusted to about 1.2 mol/L with potassium chloride, and stirred at room temperature for 1 hour. The manganese oxide material is obtained by washing and drying.

After testing, TMn was 48.85%, K content was 8.6%, and Ca content was 9.2%. The molar ratio of other metal elements such as K and Ca to manganese is 0.5. Y(Mn ²⁺ )/Y(Mn ⁴⁺ )=0.05 was measured. The expression is K _0.248 Ca _0.259 Mn ²⁺ _0.05 Mn ⁴⁺ _0.95 O ₂ . 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. Or 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. 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.

It can be seen from the analysis of the XRD detection results that 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.

50g of cylindrical manganese oxide material was placed in a fixed bed reactor with a diameter of 30mm, and was carried by dry air carrying 250ppm CO, 1ppm HCHO, 1ppm O ₃ , at 65 ° C, GHSV 5000h ^-1 continuous The concentration of CO, HCHO and O _{3 at the} outlet was measured for 1 h. The conversion rates of CO, HCHO, and O ₃ were both 100%.

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. When used, 50-100 °C industrial exhaust containing 0.1-0.4% by volume of CO, 0.5-1.5% by volume of VOCs and 0.5-1% by volume of O3 is introduced into GHSV 1000-4000h ^-1 , CO, VOCs And O3 removal rate can reach more than 99%.

Example 10

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.

After testing, 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%, and 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 . 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. Or 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. 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 7%. The main phase structure was detected by XRD as weak crystal α-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 μm, 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 analysis of the XRD detection results shows that 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.

50g of manganese oxide material was placed in a fixed-bed reactor with a diameter of 30mm, and the outlet CO was continuously tested by carrying 250ppm CO, 1ppm HCHO, 1ppm O ₃ from dry air at room temperature and GHSV 5000h ^-1 . , HCHO, O ₃ concentration 1h. The conversion rates of CO, HCHO and O ₃ were both 100%.

Example 11

air purifier.

See Figures 15 and 16.

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. Second filter element 5 and outlet 6. 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. Wherein 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. When 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. When 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. 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. In the purification unit 3 of the air cleaner of the rotary vane fan 4, the second filter unit 5 and the outlet 6.

Each of the above air purifiers using the manganese oxide materials prepared in Examples 1-10 was tested in accordance with GB/T 18801-2015 "Air Purifier". And in the same type of air purifier using other commercially available purification materials, in accordance with GB/T18801-2015 "air purifier" for formaldehyde removal detection and removal of grape bacteria detection. The first filter member 2 and the second filter member 5 should be removed when the sterilization rate test is performed. The test results are shown in Table 11. The test strains used in each of the sterilization rate tests in Table 11 were No. 1 Staphylococcus aureus, No. 3 and No. 5 Staphylococcus aureus.

Table 11

Finally, it should be noted that the above embodiments are only a few preferred modes listed in the present invention, and those skilled in the art should understand that the embodiments of the present invention are not limited to the above. Any equivalent transformation made on the basis of the present invention should fall within the scope of the present invention.

Claims (16)

1. A manganese oxide material having a spherical morphology composed of fiber rods including manganese dioxide, the manganese dioxide comprising a skeleton structure of α-MnO ₂ and/or amorphous manganese dioxide.
2. The manganese oxide material according to claim 1, wherein said spherical morphology has a diameter of from 0.9 to 2.2 μm. The fiber rod has a diameter of 10 to 50 nm.
3. A manganese oxide material according to claim 1, wherein said manganese oxide material has a specific surface of 85 to 300 m ² /g, an average pore diameter of 1.9 to 8 nm, and a pore volume of 0.1 to 0.5 cm ³ /g. The specific surface is preferably 130 to 220 m ² /g.
4. A manganese oxide material according to claim 1 wherein the heat stable temperature is ≥ 540 °C.
5. The manganese oxide material according to claim 1, further comprising other metal elements having a chemical formula of A _y B _z Mn ²⁺ _x Mn ⁴⁺ _1-x O ₂ , wherein A is a main group The metal element, B is a transition metal element, 0.1 ≤ x < 0.45, 0 ≤ y ≤ 0.507, 0 ≤ z ≤ 0.67. The metal element 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, and the other metal element is mainly located inside the manganese oxide material, and the transition metal element is preferably at least one of Cu, Ag, and rare earth. More preferably, the rare earth is preferably La and/or Ce.
6. A manganese oxide material according to claim 1, further comprising divalent manganese, said divalent manganese being present in a form comprising solid solution and/or adsorption, said ratio of said divalent manganese to tetravalent manganese Y(Mn ²⁺ )/Y(Mn ⁴⁺ )=0.08-1, the Y(Mn ²⁺ ) is a mass fraction of divalent manganese in the manganese oxide material, and the Y(Mn ⁴⁺ ) is The mass fraction of tetravalent manganese in the manganese oxide material.
7. A manganese oxide material according to any one of claims 1 to 6, characterized in that said manganese dioxide comprises weakly crystalline α-MnO ₂ .
8. A manganese oxide material according to claim 7, wherein said weak crystal α-MnO _{2 has} a card number of JCPDS No. 44-0141.
9. The manganese oxide material according to claim 8, characterized in that the α-MnO ₂ skeleton structure, the 16 to 26 nm diameter nanofiber rods have a spherical structure having a diameter of 1.09 to 1.55 μm; the main phase of manganese dioxide is a weak crystal α. -MnO ₂ and amorphous manganese oxide, the PDF card number of the α-MnO ₂ is JCPDS No. 44-0141, Y(Mn ²⁺ )/Y(Mn ⁴⁺ )=0.48; the specific surface area is 257.33 m ² / g, the pore diameter is 5.93 nm, the pore volume is 0.40 m ³ /g; the molar ratio of other metal elements to manganese element is 0.36, and the chemical formula 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 ; wherein most of the metal elements such as K, La, Ce, and Cu are located inside the material; the heat stable temperature is 550 ° C, and the lattice oxygen / adsorbed oxygen = 1.5.
10. A method for preparing a manganese oxide material, comprising:

    The soluble divalent manganese salt is mixed with manganese dioxide to prepare a precipitate A, and then an anion is added to obtain a precipitate B to obtain the manganese oxide material according to claim 1. The molar ratio of the soluble divalent manganese salt to the manganese dioxide is less than 1; or a divalent manganese compound is mixed with a high-valent manganese compound to prepare a precipitate A, and then an anion is added to obtain a precipitate B to obtain a manganese oxide material according to claim 1, an excess of the divalent manganese compound, and an excess of the divalent manganese compound. The molar ratio of the portion to the tetravalent manganese compound formed by the reaction is less than 1, and the high-valent manganese compound is a normal pentavalent manganese compound, a normal hexavalent manganese compound, or a n-hexavalent manganese compound.
11. A method of producing a manganese oxide material according to claim 10, wherein said anion is at least one of Cl ^- , NO ₃ ^- , and SO ₄ ^2- , and said anion concentration is ≥ 0.1 mol/L.
12. A method of producing a manganese oxide material according to claim 10, wherein the precipitate A is prepared at a temperature of from 20 to 80 ° C and a pH of > 7.
13. A method of producing a manganese oxide material according to claim 10, wherein the pH is ≥ 10 when manganese dioxide is prepared.
14. A method of preparing a manganese oxide material according to any one of claims 10-13, characterized in that it further comprises at least one of the following steps:

    Step A: The prepared precipitate B was added to other metal salts and mixed at a pH of 7 to 9, to obtain a precipitate C. The metal element in the metal salt is at least one of an alkali metal, an alkaline earth metal, and a transition metal, and at least one of a nitrate, a sulfate, a chloride, and an acetate is preferable.

    Step B: The precipitate B or C is filtered, dried, shaped and/or calcined.
15. A method of producing a manganese oxide material according to claim 14, wherein 169.3 parts of MnCO ₃ is suspended, 157.6 parts of K ₂ MnO _{4 is added} , the temperature is kept at 50 ° C, the pH is controlled to 8 - 10, and the mixture is stirred for 4 hours. The concentration of SO ₄ ^{2- was} adjusted to about 1 mol/L with sulfuric acid and stirred for 1 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.
16. A purifying device comprising an inlet (1), a purifying member (3) and an outlet (6), which are, in order of flow of gas, an inlet (1), a purifying member (3) and an outlet (6); The manganese oxide material according to claim 1 is installed in the purification member (3).

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