CN107876053B

CN107876053B - High-strength wastewater treatment catalyst and preparation method and application thereof

Info

Publication number: CN107876053B
Application number: CN201711165681.7A
Authority: CN
Inventors: 刘阳桥; 杨庆峰; 齐振一; 张涛; 宋力昕
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2017-11-21
Filing date: 2017-11-21
Publication date: 2020-12-11
Anticipated expiration: 2037-11-21
Also published as: CN107876053A

Abstract

The invention relates to a high-strength wastewater treatment catalyst, a preparation method and application thereof, wherein the preparation method comprises the following steps: the method comprises the following steps of (1) immersing a catalyst carrier in a mixed solution containing at least two inorganic salts at one time, taking out the catalyst carrier and carrying out heat treatment to obtain a reinforced catalyst carrier, wherein the inorganic salts comprise alkali metal salts or/and alkaline earth metal salts; and carrying out active component loading on the enhanced catalyst carrier to obtain the high-strength wastewater treatment catalyst. The wastewater treatment catalyst prepared by the invention has large specific surface area, high reaction activity and high strength, the compressive strength reaches 60-80N, and the use requirement of a fixed bed catalytic reactor can be met.

Description

High-strength wastewater treatment catalyst and preparation method and application thereof

Technical Field

The invention relates to a high-strength wastewater treatment catalyst, a preparation method and application thereof, and belongs to the technical field of water treatment.

Background

The advanced sewage treatment process mainly comprises a membrane separation method, activated carbon adsorption, an advanced oxidation method and the like. Because the wastewater system is complex, the wastewater treated by the membrane separation method has serious membrane pollution problem, thereby not only seriously affecting the operation stability, but also obviously increasing the operation cost. Although the activated carbon adsorption method has a good enrichment effect on most organic pollutants, the activated carbon adsorption method is very limited in application due to high regeneration cost and complex device of the activated carbon. Most importantly, the two methods only can realize the enrichment or transfer of the pollutants, and cannot completely eliminate the pollutants.

The advanced oxidation method is a method which can really realize the harmless degradation of pollutants in the true sense, thereby occupying an important position in the field of deep degradation of sewage. The traditional advanced oxidation technology is based on the oxidation technology of hydroxyl radical (. OH) (photocatalytic oxidation, catalytic wet oxidation, ozone oxidation, Fenton oxidation, electrochemical method and the like), and the essence of the technology is that OH mineralizes various pollutants in water through electron transfer, electrophilic addition, dehydrogenation reaction and the like, so that the harmful substances are degraded into CO₂、H₂O and other inorganic substances, or converting the O and the inorganic substances into low-toxicity and easily biodegradable intermediate products.

The heterogeneous catalytic oxidation is to load the active components of the catalyst on porous carriers with large surface area such as active carbon, alumina, diatom body and the like, and utilize the active components of the catalyst and H₂O₂、O₃And NaClO, etc. to generate hydroxyl radical, atomic oxygen, superoxide radical, persulfate and other matter with strong oxidizing property, and through electron transfer, electrophilic addition, dehydrogenation and other ways to mineralize various pollutants in water and degrade harmful matter into CO₂、H₂O and other inorganic substances, or converting the O and the inorganic substances into low-toxicity and easily biodegradable intermediate products. The catalyst is usually preformed in the form of spheres, rods, trilobes, etc. The preparation method of the catalyst comprises coprecipitation extrusion, impregnation method and the like.

CN201310036533.0 discloses a preparation method of an iron-supported molecular sieve type Fenton-like catalyst and application of the iron-supported molecular sieve type Fenton-like catalyst in a nitrobenzene wastewater treatment system. The 3A-Fe type molecular sieve is prepared by controlling the technical parameters of the 3A molecular sieve such as high-temperature roasting temperature, the reaction addition amount of sodium carbonate and ferrous sulfate and the like. And the nitrobenzene and the hydrogen peroxide form a heterogeneous Fenton-like catalytic oxidation system, so that the nitrobenzene wastewater is removed and mineralized.

CN201410606665.7 discloses MnO for treating phenol-containing wastewater₂-CeO₂A preparation method of a-CoO/AC ternary supported catalyst comprises the steps of adding a mixed solution of manganese acetate, cerium acetate and cobalt acetate with a certain concentration into raw coal powder, adding a binder, extruding into strips or pelletizing, and performing post-treatment such as carbonization and activation to obtain the ternary supported activated carbon catalyst with the particle size of 2-5mm, wherein the ternary supported activated carbon catalyst is used for catalyzing ozone to oxidize phenolic wastewater.

The activity, selectivity, stability and the like of the catalyst are important for the practical application of the catalyst, and another very important catalyst index is the mechanical strength of the catalyst. The waste water treatment catalytic device is usually a fixed bed or a fluidized bed reactor, the catalyst in the fixed bed has high compressive strength to avoid bed pressure drop increase caused by catalyst crushing, and the catalyst in the fluidized bed is easy to generate mutual friction and pulverization under a flowing state. The high-strength catalyst can reduce the replacement and the support of the catalyst, and also ensures that the catalyst cannot be damaged due to abrasion and impact in the carrying process, thereby having important significance for ensuring the production stability and improving the economic benefit. The catalyst prepared by the conventional extrusion molding method and the like has low strength, and a new technological method for improving the strength of the catalyst is urgently needed to be developed.

The factors influencing the strength of the catalyst are many, including the types and the adding amounts of a binder, an extrusion aid and a peptizing agent, the types of active particles and catalyst carriers of the catalyst, the size of crystal grains of the catalyst, the crystallinity and the like.

CN201310023136.X discloses a method for improving the strength of a molecular sieve catalyst, namely treating an extruded or ball-rolled molded molecular sieve catalyst by using an acid solution with a pH value of 0.5-4 at 100-300 ℃ for 1-200 hours, wherein the weight ratio of the acid solution to the molded molecular sieve catalyst is 3-100: 1; and drying and roasting the treated molded molecular sieve catalyst to obtain a finished product catalyst. The method can be used for the industrial production of the molecular sieve catalyst.

CN00810518.9 discloses two methods for reducing the wear loss rate of fischer-tropsch catalysts: one is to adoptThe catalyst is calcined after being soaked in an acid solution with the pH value of 1-5, preferably 1-3, and the acid is usually nitric acid, so that a large amount of NOx gas is released during calcination treatment of the catalyst, and air pollution is caused; the other is to introduce a small amount of titanium oxide before boehmite crystallization to make TiO₂The total content in the catalyst reaches 800-2000 ppm.

CN102211023A discloses a preparation method of a high-strength carbon nanotube supported platinum catalyst suitable for industrial application, comprising: a pretreatment step: heating and refluxing the primary carbon nano tube in a mixed acid (volume ratio is 3:1) of concentrated sulfuric acid (mass concentration is 98%) and concentrated nitric acid (mass concentration is 60-63%), at the temperature of 100-130 ℃, and then filtering, washing and drying; a dipping step: mixing the pretreated carbon nano tube with a chloroplatinic acid solution, standing for 24 hours, adding absolute ethyl alcohol with the total volume not more than 50%, evaporating the solvent by using a rotary evaporator, and crushing to obtain particles of 80-100 meshes; ③ a reduction step: treating at 350 deg.C for 2 hr in hydrogen gas flow, cooling to room temperature, and adding 20% N₂Passivation in air for 1 hour. The obtained catalyst has good catalytic activity for the nitrobenzene hydrogenation reaction, and the crushing strength reaches 20N/mm.

At present, the means for improving the strength of the catalyst mainly comprise the optimization of a binder formula, the adoption of methods such as tabletting and the like for forming, high-temperature sintering and the like. However, the tabletting process is complex, high in energy consumption and low in yield, and is not suitable for large-scale production. High temperature sintering significantly increases energy consumption, and material phases may change at high temperature, thereby affecting catalyst performance. Binders can improve catalyst strength, but organic binder removal temperatures are higher and inorganic binders can introduce impurities into the catalyst material.

Disclosure of Invention

Aiming at the problems of poor pressure resistance and abrasion resistance of the catalyst for wastewater treatment and the like, the invention aims to provide a high-strength wastewater treatment catalyst which is low in energy consumption, simple to operate and suitable for using a formed catalyst carrier, and a preparation method and application thereof.

In one aspect, the present invention provides a method for preparing a high-strength wastewater treatment catalyst, comprising:

the method comprises the following steps of (1) immersing a catalyst carrier in a mixed solution containing at least two inorganic salts at one time, taking out the catalyst carrier and carrying out heat treatment to obtain a reinforced catalyst carrier, wherein the inorganic salts comprise alkali metal salts or/and alkaline earth metal salts;

and carrying out active component loading on the enhanced catalyst carrier to obtain the high-strength wastewater treatment catalyst.

The invention makes the catalyst carrier load the mixture of alkali metal or alkaline earth metal salt in the channel structure by simply mixing inorganic salt (such as alkali metal salt or/and alkaline earth metal salt) liquid phase impregnation to the catalyst carrier (such as porous alumina, active carbon, etc.) with porous channel structure. Then through calcination (heat treatment), the migration and mass transfer of active ingredients in the catalyst carrier components are promoted, the mechanical property of the carrier is improved, and the characteristics of high specific surface area and high pore volume of the catalyst carrier are retained. Then based on the catalyst carrier after heat treatment, the active component is loaded, so that the compressive strength and the wear resistance of the catalyst loaded with the active component are also obviously improved, and the catalyst completely adapts to the use requirements of a fixed bed and a fluidized bed wastewater treatment reactor.

Preferably, the temperature of the primary dipping is 5-90 ℃ and the time is 1-200 hours.

Preferably, the temperature of the heat treatment is 150 to 600 ℃ and the time is 0.5 to 20 hours.

Preferably, the alkali metal salt is at least one of halide, sulfate, carbonate, nitrate and phosphate of alkali metal, and the alkaline earth metal salt is at least one of halide, sulfate, carbonate, nitrate and phosphate of alkaline earth metal.

Preferably, the catalyst support comprises porous alumina or activated carbon.

Preferably, the mass concentration of the inorganic salt is 0.01-20 wt%, and the mass ratio of the mixed solution to the catalyst carrier is (0.3-100): 1.

preferably, the load of the active component is to dip the reinforced catalyst carrier into a salt solution containing the active component for the second time, take out the catalyst carrier, and sinter the catalyst carrier for 2 to 8 hours at 300 to 800 ℃ to obtain the high-strength wastewater treatment catalyst.

Also, preferably, the active component is iron ion or/and cerium ion, and preferably the salt containing the active component is at least one of ferric nitrate, ferric chloride, ferric citrate, cerium nitrate and cerium chloride.

In addition, preferably, the total concentration of the active components is 0.2-8 mol/L, and the mass ratio of the salt solution containing the active components to the reinforced catalyst carrier is (0.5-20): 1.

in another aspect, the present invention also provides a high-strength wastewater treatment catalyst prepared according to the above method, comprising a catalyst support, and iron oxide or and cerium oxide, and alkali metal oxide or/and alkaline earth metal oxide supported on the surface of the catalyst support.

On the other hand, the invention also provides a high-strength wastewater treatment catalyst prepared by the method for catalytic oxidation of refractory organic pollutants in industrial wastewater by hydrogen peroxide, ozone and NaClO.

The invention mainly has the following beneficial effects:

the preparation method of the high-strength wastewater treatment catalyst provided by the invention has the advantages that the pretreatment temperature of the carrier is low, only 100-400 ℃ is needed, and the energy is greatly saved;

NO NO is produced during the catalyst carrier strengthening treatment₂And the like, and has environmental friendliness;

the preparation method of the catalyst has simple process, does not need expensive equipment and is easy for large-scale production;

the prepared wastewater treatment catalyst has large specific surface area, high reaction activity and high strength, the compressive strength reaches 60-80N, and the use requirement of a fixed bed catalytic reactor can be met.

The preparation method of the high-strength wastewater treatment catalyst adopts low-cost processes such as impregnation, low-temperature calcination and the like, so that the preparation cost of the catalyst is greatly reduced; the improvement of the catalyst strength effectively slows down the abrasion and pulverization of the catalyst, reduces the consumption of the catalyst in a fixed bed reactor and a fluidized bed reactor, reduces the pressure drop, reduces the operation cost of the device, ensures the stability and the safety of the operation of the device, and has important significance for improving the process level of wastewater catalytic oxidation treatment, reducing the energy consumption and the like;

the method for preparing the high-strength wastewater treatment catalyst provided by the invention does not adopt toxic and corrosive treating agents, does not generate toxic gas in the calcining process, and does not cause secondary harm to the environment. The catalyst carrier is only subjected to strengthening treatment by adopting low-concentration cheap inorganic salt, so that the treatment cost is low; the heat treatment temperature is lower, the energy is saved, and the average improvement amplitude of the catalyst strength reaches 20-80%. Different from the modification method before catalyst forming, such as optimizing the binder, tabletting, raising the sintering temperature and the like, the method provided by the invention can be used for mechanically reinforcing the formed catalyst. In addition, the catalyst preparation method provided by the invention has no obvious influence on the specific surface area of the catalyst while improving the strength. The catalyst can be used for catalyzing organic pollutants in hydrogen peroxide, ozone and sodium hypochlorite in a fixed bed or a fluidized bed to oxidize various industrial wastewater, and the safety and stability of catalytic reaction are ensured due to excellent mechanical properties of the catalyst.

Drawings

FIG. 1 is a photograph of the high strength wastewater treatment catalyst prepared in example 5 after shaking at 140rpm/24 h; FIG. 2 is a photograph showing a comparison of the high-strength wastewater treatment catalyst prepared in comparative example 3 after shaking at 140rpm/24 h.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

The invention provides a preparation method of a high-strength wastewater treatment catalyst, aiming at the problems that the pressure drop of a fixed bed reactor is large and difficult to adapt to the use of a long-time fixed bed catalytic oxidation reaction, the catalyst is easy to break and the abrasion resistance of a fluidized bed catalyst is poor due to the low mechanical strength of the existing wastewater treatment catalyst. Specifically, the porous alumina and activated carbon carrier is impregnated by using a mixed solution of two or more inorganic salts, and a mixture of a small amount of alkali metal or alkaline earth metal salt is loaded in a pore channel structure of the catalyst carrier, and then heat treatment is carried out at a lower temperature, so that mass transfer and migration of components of the catalyst carrier are promoted, and the mechanical property of the carrier is improved. Then, the heat-treated catalyst carrier is washed and dried, and then immersed in a salt solution containing an active component (a solution containing iron ions or/and cerium ions, preferably a solution containing a metal salt such as ferric nitrate, ferric chloride, ferric citrate, cerium nitrate, cerous chloride, etc.), and decomposed at elevated temperature to obtain a catalyst for wastewater treatment having high mechanical strength. The high-strength wastewater treatment catalyst prepared by the invention can obviously improve the oxidation capability of hydrogen peroxide, NaClO, ozone and the like on refractory organic matters in sewage, and realize the standard-reaching discharge of the first-grade A of the wastewater.

The following exemplarily illustrates a method for preparing the high-strength catalyst for wastewater treatment according to the present invention.

The catalyst carrier is dipped into a mixed solution containing at least two inorganic salts at one time, taken out, washed by water or alcohol and then dried. The drying temperature can be 20-150 ℃, preferably 50-140 ℃, and the drying time can be 2-24 hours. Then carrying out heat treatment to obtain the reinforced catalyst carrier. The catalyst carrier has a porous pore channel structure, and can be porous alumina or activated carbon carrier. The temperature of the primary dipping can be 5-90 ℃, preferably 5-80 ℃, and the time can be 1-200 hours. The temperature of the heat treatment can be 150-600 ℃, preferably 150-500 ℃, and the time can be 0.5-20 hours, preferably 1-8 hours. The shape of the catalyst carrier includes, but is not limited to, a sphere, a stripe, a clover shape, a granule, a honeycomb, and the like. The catalyst support may be of any size. The inorganic salt may include an alkali metal salt or/and an alkaline earth metal salt. The alkali metal salt may be at least one of a halide, sulfate, carbonate, nitrate and phosphate of an alkali metal. The alkaline earth metal salt may be at least one of a halide, sulfate, carbonate, nitrate, and phosphate of an alkaline earth metal. The total mass concentration of the alkali metal salt in the mixed solution containing at least two inorganic salts is 0.1-20 wt%, wherein the molar percentage of any inorganic salt is between 1-99%, and preferably between 20-80 mol%. The mass ratio of the mixed solution to the catalyst carrier can be (0.3-100): 1.

as an example, a porous alumina or activated carbon support (sphere, strip, clover shape, granule, honeycomb) is impregnated (for example, impregnated at 50 to 90 ℃ for 6 to 24 hours) in an alkali metal or alkaline earth metal salt mixed solution (for example, the total mass concentration of the salt is 0.1 to 20 wt%, wherein the molar percentage of any salt is between 1 to 99%), and dried in air (for example, dried at 50 to 140 ℃ for 2 to 24 hours); and (3) placing the catalyst carrier precursor in a muffle furnace for heat treatment at the temperature of 150-600 ℃ for 0.5-20 hours. It should be noted that the atmosphere for the heat treatment is selected differently depending on the catalyst support. For example, in an air atmosphere (for alumina supports) or in a tube furnace under vacuum or N₂And roasting the mixture for 1 to 8 hours at the temperature of between 150 and 500 ℃ in an Ar inert atmosphere (aiming at the activated carbon carrier), and naturally cooling the mixture to the room temperature. And (3) washing and drying the formed catalyst carrier which is impregnated with the mixed salt and roasted.

And carrying out active component loading on the enhanced catalyst carrier to obtain the high-strength wastewater treatment catalyst. In particular, Fe can be prepared by an impregnation method₂O₃、CeO₂And the like. And (2) secondarily dipping the reinforced catalyst carrier (for example, secondarily dipping at 5-50 ℃ for 6-24 hours) into a precursor solution (a salt solution containing Fe ions, Ce ions and the like of the active component of the catalyst) of the active component, and then taking out and drying (for example, drying at 50-140 ℃ for 2-24 hours) to obtain the high-strength wastewater treatment catalyst precursor. The active component can be iron ions or/and cerium ions. The precursor solution of the active component can be an aqueous solution or an ethanol solution containing metal salts such as ferric nitrate, ferric chloride, ferric citrate, cerium nitrate, cerium chloride and the like. The total concentration of metal ions (namely, the active component, iron ions or/and cerium ions and the like) in the precursor solution of the active component can be 0.2-8 mol/L. The mass ratio of the precursor solution of the active component (salt solution containing the active component) to the reinforced catalyst carrier is (0.5-20): 1.

sintering the high-strength wastewater treatment catalyst precursor for 2-8 hours at 300-800 ℃ (preferably 300-550 ℃), andand obtaining the high-strength wastewater treatment catalyst. It should be noted that the atmosphere for the heat treatment is selected differently depending on the catalyst support. Putting the catalyst precursor in a muffle furnace in air atmosphere (alumina carrier) or in a tube furnace in vacuum or N₂And sintering the mixture for 2 to 8 hours at the temperature of 300 to 550 ℃ in an Ar inert atmosphere (an activated carbon carrier), and naturally cooling the mixture to room temperature to obtain the high-strength catalyst for the advanced treatment of the industrial wastewater.

In general, the invention soaks the formed catalyst carrier (alumina, active carbon, etc.) with the mixed solution of two or more inorganic salts, washes and dries after heat treatment at a certain temperature, and the compression strength and the wear-resisting strength are greatly improved. The reinforced catalyst carrier is soaked in a salt solution containing catalyst active components such as Fe ions, Ce ions and the like, dried and roasted in the atmosphere of air, vacuum, nitrogen or argon, so that the high-strength wastewater treatment catalyst is obtained. The wastewater treatment catalyst can be used for catalyzing hydrogen peroxide, ozone, sodium hypochlorite and the like in a fixed bed or fluidized bed reactor to efficiently remove organic pollutants, ammonia nitrogen and the like in various types of industrial wastewater. The high-strength wastewater treatment catalyst prepared by the embodiment comprises a catalyst carrier, iron oxide or/and cerium oxide loaded on the catalyst carrier, and alkali metal or/and alkaline earth metal oxide. Wherein the mass content of the iron tungsten oxide or/and the cerium oxide can be 1-20 wt%. The mass content of the alkali metal oxide or/and the alkaline earth metal oxide can be 0.05-2 wt%, and the balance is a catalyst carrier.

The method for preparing the high-strength catalyst for wastewater treatment provided by the invention has the advantages that the prepared catalyst has good mechanical property, can meet the use requirements of a fixed bed reactor and a fluidized bed reactor in wastewater treatment, and has long service life; the production process is clean and environment-friendly; the catalyst carrier is treated by inorganic salt, the roasting temperature is low and only needs 100-400 ℃, and energy is greatly saved; the related catalyst preparation method has simple process, does not need expensive equipment and is easy for large-scale production; the catalyst has large specific surface area and high activity, can efficiently catalyze pollutants such as COD (chemical oxygen demand) and ammonia nitrogen in oxidation wastewater such as hydrogen peroxide, ozone and sodium hypochlorite, and has excellent decolorization effect.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Example 1

300g of activated alumina balls (diameter 2-4mm, specific surface area 240 m)²Per g, the crushing strength is 50N) is soaked in 400g of NaCl-KCl aqueous solution with the total salt concentration of 1 wt% (the molar ratio of NaCl to KCl is 1:1) for 12 hours, and naturally dried after being drained; then drying at 120 ℃ for 15 hours, and roasting in a muffle furnace at 300 ℃ for 3 hours; after the temperature is reduced to room temperature, washing with water for many times, draining and naturally drying; then dried at 120 ℃ for 10 hours to finally obtain the reinforced catalyst carrier with the specific surface area of 225m²(iv)/g, crushing strength 72N.

Soaking the treated alumina carrier in 150ml of 30% ferric nitrate nonahydrate aqueous solution for 12h, draining, and naturally drying; then dried at 120 ℃ for 15 hours and calcined in a muffle furnace at 400 ℃ for 6 hours to finally obtain the alumina-supported iron oxide catalyst for the test. The catalyst of iron oxide supported on alumina prepared in this example had an iron oxide content of 12 wt%, a sum of sodium oxide and potassium oxide of 0.2 wt%, and the balance of alumina support.

The obtained alumina-supported iron oxide catalyst material was characterized by a specific surface area and a crush strength, and the specific surface area was found to be 202m²(iv)/g, crush strength 79.0N.

100mL of the catalyst is loaded in an organic glass reaction column with the diameter of 30mm and the length of 200mm, and the treatment effect of the catalyst on organic pollutants in alcohol wastewater of a certain brewery is tested at normal temperature and normal pressure. The initial COD of the wastewater was 120mg/L, the total amount of the experimental wastewater was 300ml, a total of 0.6 ml of NaClO solution (10 wt% of available chlorine, 0.3ml added at the beginning of the reaction and 30min after the reaction) was added, and the pH was controlled to about 8.0 using sulfuric acid or sodium hydroxide solution. After one hour of treatment, the chemical oxygen demand of the wastewater is reduced to 36mg/L, and the removal rate of COD is 70%.

Example 2

300g of alumina in the form of strips (diameter 2mm, length 5mm, specific surface area 240 m)²Per g, the crushing strength is 40N) is soaked in 450g of NaCl-KCl aqueous solution with the total salt concentration of 0.5 wt% (the molar ratio of NaCl to KCl is 1:1) for 12 hours, and naturally dried after being drained; then drying at 120 ℃ for 15 hours, and roasting in a muffle furnace at 350 ℃ for 3 hours; after the temperature is reduced to room temperature, washing with water for many times, draining and naturally drying; then dried at 120 ℃ for 10 hours to finally obtain the reinforced catalyst carrier (with the specific surface area of 228 m)²In terms of/g, the crush strength was 70.2N).

Soaking the treated alumina carrier in 150ml of mixed aqueous solution of 30% by mass of ferric nitrate nonahydrate and cerium nitrate (the molar ratio of the ferric nitrate to the cerium nitrate is 10:1) for 12h, draining, and naturally drying; then dried at 120 ℃ for 15 hours, and then calcined in a muffle furnace at 400 ℃ for 6 hours to finally obtain the alumina-supported iron oxide-cerium oxide catalyst for the test. In the catalyst of iron oxide-cerium oxide supported on alumina prepared in this example, the content of iron oxide-cerium oxide was 13 wt%, the content of sodium oxide and potassium oxide were both 0.1 wt%, and the rest was alumina carrier.

The above iron oxide-cerium oxide-supported alumina catalyst material was characterized by a specific surface area and a crush strength, and the specific surface area was found to be 210.3m²(iv)/g, crushing strength 69.4N.

100mL of the catalyst is loaded in an organic glass reaction column with the diameter of 30mm and the length of 200mm, and the treatment effect of the catalyst on organic pollutants in alcohol wastewater of a certain brewery is tested at normal temperature and normal pressure. The initial COD of the wastewater was 120mg/L, the total amount of the experimental wastewater was 300ml, a total of 0.6 ml of NaClO solution (10 wt% of available chlorine, 0.3ml added at the beginning of the reaction and 30min after the reaction) was added, and the pH was controlled to about 8.0 using sulfuric acid or sodium hydroxide solution. After one hour of treatment, the chemical oxygen demand of the wastewater is reduced to 32mg/L, and the removal rate of COD is 73.3%.

Example 3

100g of a strip-shaped activated carbon (diameter 2mm, length 5mm, specific surface area 700 m)²Strength 90%/g) in 200g of Na having a total salt concentration of 0.5% by weight₂SO₄-K₂SO₄Mixed aqueous solution (Na)₂SO₄And K₂SO₄Dipping for 12 hours in a molar ratio of 1:1), draining and naturally drying; then drying at 120 ℃ for 15 hours, placing in a tube furnace, and roasting at 400 ℃ for 3 hours under a vacuum condition; after the temperature is reduced to room temperature, washing with water for many times, draining and naturally drying; then dried at 120 ℃ for 10 hours to finally obtain a modified catalyst carrier (specific surface area of 694 m)²In terms of/g, 94% strength).

Soaking the treated activated carbon carrier in 150ml of 30% ferric nitrate nonahydrate aqueous solution for 12h, draining, and naturally drying; then drying at 120 ℃ for 15 hours, and roasting at 400 ℃ for 6 hours in a tubular furnace under vacuum condition to finally obtain the active carbon supported iron oxide catalyst for the test. The content of iron oxide in the activated carbon-supported iron oxide catalyst prepared in this example was 15 wt%, the content of sodium oxide and potassium oxide were each 0.14 wt%, and the balance was an activated carbon support.

The activated carbon-supported iron oxide catalyst prepared in this example was found to have a specific surface area of 718.3m²In terms of/g, the strength was 95%.

100mL of the catalyst is loaded in an organic glass reaction column with the diameter of 30mm and the length of 200mm, and the treatment effect of the catalyst on organic pollutants in alcohol wastewater of a certain brewery is tested at normal temperature and normal pressure. The initial COD of the wastewater is 120mg/L, the total amount of the experimental wastewater is 300ml, 1.5 ml of hydrogen peroxide (the content of hydrogen peroxide is 30 wt%, 0.75ml is added respectively at the beginning of the reaction and after 30min of the reaction), and the pH is controlled to be about 7.0 by adopting sulfuric acid or sodium hydroxide solution. After one hour of treatment, the chemical oxygen demand of the wastewater is reduced to 49mg/L, and the removal rate of COD is 59.2%.

Example 4

100g of spherical activated carbon (diameter 2-3mm, specific surface area 840 m)²(90%) in 200g NaCl-KCl aqueous solution (NaCl/KCl molar ratio is 1:1) with total salt concentration of 2.0 wt% for 12h, draining, and naturally drying; then drying at 120 ℃ for 15 hours, placing in a tube furnace, and roasting at 300 ℃ for 3 hours under a vacuum condition; after the temperature is reduced to room temperature, washing with water for many times, draining and naturally drying; then dried at 120 ℃ for 10 hours to finally obtain a modified catalyst carrier (specific surface area: 820 m)²In g, strength 95%).

Soaking the treated alumina carrier in 150ml of 30% ferric nitrate nonahydrate aqueous solution for 12h, draining, and naturally drying; then drying at 120 ℃ for 15 hours, and roasting at 450 ℃ for 6 hours in a tubular furnace under vacuum condition to finally obtain the active carbon supported iron oxide catalyst for the test.

The activated carbon-supported iron oxide catalyst prepared in this example was found to have a specific surface area of 813m²In terms of/g, the strength was 95%.

Testing the treatment effect of the alcohol wastewater treatment agent on organic pollutants in alcohol wastewater of a certain winery. The initial COD of the wastewater is 120mg/L, the total amount of the experimental wastewater is 300ml, 1.5 ml of hydrogen peroxide (the content of hydrogen peroxide is 30 wt%, 0.75ml is added respectively at the beginning of the reaction and after 30min of the reaction), and the pH is controlled to be about 7.0 by adopting sulfuric acid or sodium hydroxide solution. After one hour of treatment, the chemical oxygen demand of the wastewater is reduced to 46mg/L, and the removal rate of COD is 61.7%.

Example 5

100g of granular activated carbon (6-15 meshes, specific surface area 840 m)²(90%) in 200g LiCl-KCl aqueous solution with total salt concentration of 2.0 wt% (LiCl/KCl molar ratio of 1:1), soaking for 12h, draining, and naturally drying; then drying at 120 ℃ for 15 hours, placing in a tube furnace, and roasting at 350 ℃ for 3 hours under a vacuum condition; after the temperature is reduced to room temperature, washing with water for many times, draining and naturally drying; then dried at 120 ℃ for 10 hours to finally obtain a modified catalyst carrier (specific surface area: 832 m)²In terms of/g, 94% strength).

Soaking the treated activated carbon carrier in 150ml of 30% ferric nitrate nonahydrate aqueous solution for 12h, draining, and naturally drying; then drying at 120 ℃ for 15 hours, and roasting at 450 ℃ for 6 hours in a tubular furnace under vacuum condition to finally obtain the active carbon supported iron oxide catalyst for the test.

The activated carbon-supported iron oxide catalyst prepared in this example was found to have a specific surface area of 813m²In terms of/g, the strength is 94%.

8g of the catalyst is loaded in a fluidized bed organic glass reaction column with the diameter of 30mm and the length of 100mm, and the treatment effect of the catalyst on organic pollutants in printing and dyeing wastewater of a certain clothing factory is tested at normal temperature and normal pressure. Printing and dyeing wastewater with the total amount of 300mL is pumped from the lower part of the reactor, the initial COD of the wastewater is 113mg/L, and the flow rate of the wastewater is controlled to be 1L/min; ozone is prepared by adopting a small air source ozone generator, is introduced through a microporous aeration plate at the lower end of the reactor, and passes through the reactor in the same direction as the wastewater. The pH is controlled to be about 7.0 by adopting sulfuric acid or sodium hydroxide solution in the reaction process. After one hour of treatment, the chemical oxygen demand of the wastewater is reduced to 46mg/L, and the removal rate of COD is 59.3%.

Comparative example 1 Al without NaCl-KCl mixed salt treatment of Carrier₂O₃Supported iron oxide catalyst with reference to example 1, 300g of activated alumina balls (diameter 2-4mm, specific surface area 240 m)²Per gram, the crushing strength is 50N), soaking in 150ml of 30 percent ferric nitrate nonahydrate aqueous solution for 12 hours without any treatment, draining and naturally airing; then dried at 120 ℃ for 15 hours, and then calcined in a muffle furnace at 400 ℃ for 6 hours, finally obtaining the alumina-supported iron oxide catalyst used in the test. The iron oxide-supported alumina catalyst prepared in comparative example 1 had an iron oxide content of 12 wt% and the balance of an alumina carrier.

Al not treated with NaCl-KCl mixed salt was measured₂O₃The supported iron oxide catalyst had a crush strength of 52.2N and a specific surface area of 205.2m²/g。

As can be seen from comparison with the results of example 1, the crush strength of the catalyst treated with the NaCl-KCl mixed solution of example 1 was increased by 51.2% as compared with the comparative example, and the specific surface area of the catalyst was not significantly changed.

Comparative example 2 nitric acid treated Al as carrier₂O₃Supported iron oxide catalyst

Referring to example 1, 300g of activated alumina balls (2-4 mm in diameter, 240m in specific surface area)²Per g, the crushing strength is 50N) is soaked in 400g of 0.1mol/L nitric acid water solution for 12 hours, and naturally dried after being drained; then drying at 120 ℃ for 15 hours, and roasting in a muffle furnace at 300 ℃ for 3 hours; after the temperature is reduced to room temperature, washing with water for many times, draining and naturally drying; then dried at 120 ℃ for 10 hours to finally obtain a modified catalyst carrier (with a specific surface area of 232 m)²,/g, crush strength 57.6N).

Soaking the treated alumina carrier in 150ml of 30% ferric nitrate nonahydrate aqueous solution for 12h, draining, and naturally drying; then dried at 120 ℃ for 15 hours and calcined in a muffle furnace at 400 ℃ for 6 hours to finally obtain the alumina-supported iron oxide catalyst for the test. The iron oxide content of the alumina-supported iron oxide catalyst prepared in this example was 12 wt% and the alumina content was 88 wt%.

The nitric acid-treated Al of the carrier prepared in comparative example 2 was measured₂O₃The supported iron oxide catalyst had a crush strength of 58.9N, which was 12.8% higher than the catalyst prepared with the untreated support of comparative example 1; and the crushing strength was 25.4% lower than that of the catalyst 79.0N prepared from the NaCl-KCl mixed salt treated carrier in example 1.

The above results indicate that the HNO proposed in the present comparative example 2₃The treatment method can improve the crushing strength of the catalyst to a certain extent. The crushing strength of the wastewater treatment catalyst prepared by the NaCl-KCl mixed salt treatment method provided by the invention is far higher than that of HNO₃Treatment method and avoidance of HNO₃NO emitted during calcination₂Toxic gas, and no harm to environment.

Comparative example 3 activated carbon-supported iron oxide catalyst with non-mixed salt treatment as support

Referring to example 5, 100g of granular activated carbon (6-15 mesh)Specific surface area of 840m²Per gram, strength 90%) in 150ml of 30% ferric nitrate nonahydrate aqueous solution for 12h, draining, and naturally drying; then drying at 120 ℃ for 15 hours, and roasting at 450 ℃ for 6 hours in a tubular furnace under vacuum condition to finally obtain the active carbon supported iron oxide catalyst for the test.

The specific surface area of the activated carbon-supported iron oxide catalyst, the carrier of which was prepared in this comparative example and was not subjected to mixed salt treatment, was determined to be 820m²In terms of a specific gravity, the strength was 91%. As can be seen from comparison with the results of example 5, the strength of the catalyst was improved by 3.3% without significant change in the specific surface area of the catalyst by treatment with the LiCl-KCl mixed solution.

10g of the activated carbon-supported iron oxide catalysts prepared in example 5 and comparative example 3 were added to 100mL of deionized water, respectively, and the mixture was shaken for 1 hour at 140rpm on a shaker. A comparison of the two samples is shown in FIGS. 1 and 2. FIG. 1 shows that the activated carbon-supported iron oxide catalyst of example 5, in which the carrier is treated with LiCl-KCl mixed salt, is still clear after shaking for 1 hour, and the catalyst is not abraded; in contrast, in the catalyst of comparative example 3 in which the carrier was not treated with mixed salts, water was cloudy and the catalyst particles were abraded by collision with each other more severely (see FIG. 2). The comparison shows that the abrasion resistance of the catalyst is obviously improved after the mixed salt treatment.

In the invention, the specific surface areas of the catalyst carrier, the modified catalyst carrier and the obtained catalyst are measured by a Quadrasorb SI (American Congta) specific surface instrument by using a nitrogen adsorption method; the crushing strength of the alumina carrier and the supported catalyst thereof is measured by a DLII type intelligent particle strength tester, more than 50 catalysts are randomly selected to measure the strength value, and the results are averaged; the strength of the activated carbon carrier and the supported catalyst thereof is determined by adopting a THQ-8000 activated carbon strength determinator and a GBT 20451-.

Comparative example 4A 300g activated alumina sphere (2 to 4mm in diameter, 240m in specific surface area)²(50N in terms of crush strength) was immersed in 400g of an aqueous solution containing 1 wt% NaCl-KCl (molar ratio of NaCl to KCl: 1) and 30 wt% ferric nitrate nonahydrate for 12 hours, drained and then naturally dried. Then drying at 120 deg.C for 15 hr, standingRoasting for 6 hours at 400 ℃ in a muffle furnace to finally obtain the alumina-supported iron oxide catalyst for the test.

The obtained alumina-supported iron oxide catalyst material was characterized by a specific surface area and a crush strength, and the specific surface area was found to be 205m²(iv)/g, crush strength 55.4N. The comparison result with the example 1 shows that the strength of the catalyst obtained by adopting the step-by-step secondary impregnation method is 29.9 percent higher than that of the catalyst obtained by adopting the primary impregnation method, the change of the specific surface area is not large, and the secondary impregnation method is more favorable for enhancing the mechanical property.

100mL of the catalyst is loaded in an organic glass reaction column with the diameter of 30mm and the length of 200mm, and the treatment effect of the catalyst on organic pollutants in alcohol wastewater of a certain brewery is tested at normal temperature and normal pressure. The initial COD of the wastewater was 120mg/L, the total amount of the experimental wastewater was 300ml, a total of 0.6 ml of NaClO solution (10 wt% of available chlorine, 0.3ml added at the beginning of the reaction and 30min after the reaction) was added, and the pH was controlled to about 8.0 using sulfuric acid or sodium hydroxide solution. After one hour of treatment, the chemical oxygen demand of the wastewater is reduced to 35mg/L, and the removal rate of COD is 70.8%. Compared with the example 1, the method of the second impregnation has the advantages that the mechanical property of the catalyst obtained by the method of the first impregnation is obviously improved, and the catalytic property is basically equal.

Claims

1. A preparation method of a high-strength wastewater treatment catalyst is characterized by comprising the following steps:

the method comprises the following steps of immersing a catalyst carrier in a mixed solution containing Na salt and K salt or a mixed solution containing Li salt and K salt at one time, taking out the catalyst carrier and carrying out heat treatment to obtain a reinforced catalyst carrier, wherein the Li salt is at least one of Li halide, sulfate, carbonate, nitrate and phosphate, the Na salt is at least one of Na halide, sulfate, carbonate, nitrate and phosphate, and the K salt is at least one of K halide, sulfate, carbonate, nitrate and phosphate;

loading active components on the reinforced catalyst carrier to obtain the high-strength wastewater treatment catalyst;

the catalyst support comprises porous alumina or activated carbon;

the temperature of the heat treatment is 150-600 ℃, and the time is 0.5-20 hours;

the active component is iron ions or/and cerium ions;

the total mass concentration of Na salt and K salt in the mixed solution containing Na salt and K salt is 0.1-2 wt%, wherein the molar ratio of Na salt to K salt is 1: 1;

the total mass concentration of the Li salt and the K salt in the mixed solution containing the Li salt and the K salt is 0.1-2 wt%, wherein the molar ratio of the Li salt to the K salt is 1: 1.

2. the method according to claim 1, wherein the primary impregnation is carried out at a temperature of 5 to 90 ℃ for 1 to 200 hours.

3. The production method according to claim 1, wherein the mass ratio of the mixed solution to the catalyst carrier is (0.3 to 100): 1.

4. the preparation method according to claim 1, wherein the active component is loaded by immersing the reinforced catalyst carrier in a salt solution containing the active component for a second time, taking out the catalyst carrier, and sintering the catalyst carrier at 300-800 ℃ for 2-8 hours to obtain the high-strength wastewater treatment catalyst.

5. The method according to claim 4, wherein the active ingredient-containing salt is at least one of ferric nitrate, ferric chloride, ferric citrate, cerium nitrate and cerium chloride.

6. The preparation method according to claim 4 or 5, wherein the total concentration of the active component is 0.2 to 8mol/L, and the mass ratio of the salt solution containing the active component to the reinforced catalyst carrier is (0.5 to 20): 1.

7. a high-strength wastewater treatment catalyst produced by the production method according to any one of claims 1 to 6.

8. The high-strength wastewater treatment catalyst prepared by the preparation method according to any one of claims 1 to 6 is used for catalytic oxidation of refractory organic pollutants in industrial wastewater by hydrogen peroxide, ozone and NaClO.