CN113680349A

CN113680349A - Preparation method of coal-based active coke-based ozone catalyst for treating coking wastewater

Info

Publication number: CN113680349A
Application number: CN202111140514.3A
Authority: CN
Inventors: 邵雁; 蒋庆肯; 郭华军; 刘子豪; 姜明明; 杨振; 胡国峰; 夏阳; 刘颖
Original assignee: China City Environment Protection Engineering Ltd
Current assignee: China City Environment Protection Engineering Ltd
Priority date: 2021-09-28
Filing date: 2021-09-28
Publication date: 2021-11-23

Abstract

本发明公开了一种处理焦化废水的煤制活性焦基臭氧催化剂的制备方法，属于焦化废水处理用催化剂领域。本发明的制备方法包括以下步骤：将原煤、兰炭和活性组分研磨成细粉后混合，混合好的粉料中添加水、粘结剂、助剂进行搅拌、捏合，捏合好的捏合料进行成型，成型体通过晾晒或干燥至水分含量为5‑15％后进行炭化活化，炭化活化的催化剂上筛将粉末和碎片去除，得到催化剂成品。本发明以煤制活性焦为主要载体，兼具传统碳基催化剂、氧化铝或硅铝基催化剂优点：原料易获取、制备简单、成本较低，同时在处理焦化废水COD时有优异的效果。The invention discloses a preparation method of a coal-based active coke-based ozone catalyst for treating coking wastewater, and belongs to the field of catalysts for treating coking wastewater. The preparation method of the present invention comprises the following steps: grinding raw coal, blue charcoal and active components into fine powders and mixing them; adding water, binders and auxiliary agents to the mixed powders for stirring and kneading; After molding, the molded body is carbonized and activated by drying or drying to a moisture content of 5-15%, and the carbonized-activated catalyst is screened to remove powder and debris to obtain a finished catalyst. The invention uses coal-made activated coke as the main carrier, and has the advantages of traditional carbon-based catalysts, alumina or silicon-alumina-based catalysts: easy acquisition of raw materials, simple preparation, low cost, and excellent effects in treating coking wastewater COD.

Description

Preparation method of coal-based active coke-based ozone catalyst for treating coking wastewater

Technical Field

The invention relates to the field of catalysts for coking wastewater treatment, in particular to a preparation method of a coal-made active coke-based ozone catalyst and the coal-made active coke-based ozone catalyst prepared by the method.

Background

Coking wastewater is wastewater generated in the processes of coking, coal gas high-temperature dry distillation, purification and byproduct recovery of steel enterprises, and the wastewater contains complex inorganic and organic pollutants, such as phenols, cyanides, thiocyanides, ammonia, polycyclic aromatic hydrocarbons, polycyclic nitrogen-containing aromatic hydrocarbons, sulfur-containing heterocyclic compounds and the like, most of which are refractory, toxic and carcinogenic substances, and the traditional biochemical treatment method has poor effect of removing the substances. The ozone catalytic oxidation technology can be carried out at normal temperature and normal pressure, does not need any heat, light or high-pressure auxiliary system, is an environment-friendly advanced oxidation technology, and is particularly suitable for removing organic pollutants difficult to degrade in water.

Ozone has strong oxidation effect, the oxidation-reduction potential of the ozone is 2.07eV, although pure ozone oxidation can remove organic matters to a certain extent, the pollutant is not thoroughly treated under the condition of low utilization rate of the single ozone. The ozone catalytic oxidation technology is a novel advanced oxidation technology developed on the basis of the traditional ozone oxidation, and a catalyst is added into an ozone system, so that on one hand, the catalyst can also adsorb pollutants on the surface of the catalyst, and the capability of directly oxidizing organic matters by ozone is improved; on the other hand, the method can obviously improve the generation of hydroxyl radicals with stronger oxidizing capability in an ozone system and degrade pollutants. Ozone catalysts are generally divided into homogeneous catalysts and heterogeneous catalysts, the homogeneous catalysts are generally transition metal ions, the catalysts run away with water after treatment, and the running-away metal ions have potential environmental safety risks; the heterogeneous ozone catalyst mainly utilizes the catalytic action of solid metal, metal oxide or metal oxide loaded on a carrier, has the advantages of simple preparation, easy recovery treatment, long service life and the like, and has wide application in engineering.

The common heterogeneous ozone catalyst is generally prepared by taking active carbon or alumina or a silicon-aluminum composite material as a carrier, loading metal salts such as iron, manganese and the like on the carrier by adopting an impregnation method, and then drying, roasting and the like processes on the carrier.

When the catalyst is prepared by taking the active carbon as a carrier, the organic pollutants can be removed by utilizing the adsorption effect of the active carbon, but the catalyst is easy to run off and short in service life, and the columnar product can increase the head loss of backwashing; the catalyst prepared by the alumina or silicon-aluminum composite material has high strength and long service life, but the raw materials are expensive, the temperature required in the roasting process is higher, the energy consumption is high, the density of the catalyst is higher, the requirement on the strength of a tank device in industrial application is higher, and the cost in engineering application is higher.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a preparation method of a coal-made active coke-based ozone catalyst, the coal-made active coke-based ozone catalyst prepared by the method and the application of the catalyst in treating coking wastewater. The coal-made active coke-based ozone catalyst has the advantages that the coal-made active coke is used as a carrier, and a certain proportion of active components and auxiliaries are added by a blending type preparation process aiming at the characteristics of refractory substances such as polycyclic aromatic hydrocarbon, cyanide, nitrogen-containing heterocyclic compounds and the like contained in coking wastewater, so that the defects of short service life of the active carbon catalyst and high cost of the alumina or silicon-aluminum-based catalyst are overcome, and the coal-made active coke-based ozone catalyst which has the advantages of large specific surface area, high compressive strength, long service life, good binding property of the active components and the carrier, high stability, low cost and higher efficiency of exciting to generate hydroxyl radicals is obtained.

The purpose of the invention is realized by the following technical scheme:

a preparation method of an active coke-based ozone catalyst for coal production comprises the following steps:

(1) grinding: raw coal, semi coke and active components are mixed according to the mass ratio of (30-75): (20-60): (5-10) weighing, grinding into fine powder and mixing. The active component is a mixture of any two or more than two of manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide and cerium oxide. This step is preferably carried out in a ball mill.

(2) Stirring and kneading: and (2) adding water, a binder and an auxiliary agent into the ground and mixed powder in the step (1) for stirring and kneading, wherein the adding amount of the water accounts for 10-25% of the mass of the powder, the adding amount of the binder accounts for 10-30% of the mass of the powder, and the adding amount of the auxiliary agent accounts for 0.1-5% of the mass of the powder. The assistant is an alkaline solution containing one or more metal ions, the metal ions comprise potassium, sodium, magnesium and other metal ions, and the total metal ion solubility in the alkaline solution is preferably 100-1000 mg/L. The powder quality in the step refers to the quality of mixed powder of raw coal, semi coke and active components. This step is preferably carried out in a kneader.

(3) Molding: and (3) molding the kneaded material kneaded in the step (2). Preferably in a disk pelletizer and finally formed into round pellet shapes. The molded article obtained was air-dried or dried to a water content of 5 to 15%, and then subjected to the next step.

(4) Carbonization and activation: and (4) carbonizing and activating the molding material in the step (3). Firstly, heating a carbonization activation device to a preset temperature, enabling the molding material to have a carbonization reaction, maintaining for a period of time, and then heating to activate the molding material. The carbonization is performed in a non-oxidizing atmosphere such as nitrogen. The activation is carried out under a non-oxidizing atmosphere consisting of nitrogen gas and water vapor. This step is preferably accomplished in a carbonization activation furnace.

(5) Cooling and screening: and (4) naturally cooling the carbonized and activated catalyst in the step (4), and then sieving to remove powder and fragments to obtain a catalyst finished product. If the step (4) is completed in the carbonization and activation furnace, the carbonized and activated catalyst is taken out of the furnace and then naturally cooled; the tapping temperature is below 100 ℃, preferably below 70 ℃.

In the step (1), the raw coal can be bituminous coal or anthracite; the particle size of the fine powder is preferably 200 meshes or more.

In the step (1), the ball mill can stir and mix the raw materials by mechanically milling.

In the step (1), when the active components are any two of manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide and cerium oxide, the mass ratio of the two is preferably (1-5): (1-5).

In the step (2), the binder is preferably one or more of coal tar, pitch and glycerol.

In the step (2), the assistant is preferably a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution or a mixed aqueous solution of sodium hydroxide and potassium hydroxide.

In the step (2), the kneading time is preferably 10 to 30 min.

In the step (3), the diameter of the granules is preferably controlled to be 4-6mm, and the standard is 5 mm; when the water content of the ball material is 5-15%, the compressive strength is above 10 MPa.

In the step (3), the drying temperature is preferably 50 to 90 ℃.

In the step (4), the carbonization temperature rise rate is controlled to be 5-20 ℃/min, the carbonization reaction temperature is 500-800 ℃, and the carbonization reaction time is 0.5-3 h.

In the step (4), the activation temperature rate is controlled to be 5-20 ℃/min, the activation reaction temperature is 500-900 ℃, and the activation reaction time is 10-120 min.

In the step (4), the amount of water vapor injected is preferably 5.0 to 20mL/min/500g of molding material in a non-oxidizing atmosphere consisting of nitrogen and water vapor.

An active coke-based ozone catalyst for coal production, which is obtained by the preparation method.

The coal-made active coke-based ozone catalyst is applied to treatment of coking wastewater.

Compared with the prior art, the invention has the following advantages and beneficial effects: the invention takes coal-made active coke as a main carrier, and has the advantages of the traditional carbon-based catalyst and the traditional alumina or silicon-aluminum-based catalyst: the raw materials are easy to obtain, the preparation is simple, the cost is low, and meanwhile, the effect is excellent when the coking wastewater COD is treated.

Detailed Description

The following examples are intended to further illustrate the invention but should not be construed as limiting it. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

Example 1:

the preparation of the coal-made active coke-based ozone catalyst for treating the coking wastewater comprises the following steps:

(1) weighing and mixing bituminous coal, semi-coke and active components according to the mass ratio of 55:40:5, pouring the mixture into a ball mill, grinding the mixture into fine powder with the particle size of more than 200 meshes, and mixing the fine powder, wherein the total mass is 5 kg. The active component is a mixture consisting of copper oxide and cerium oxide, and the mass ratio of the copper oxide to the cerium oxide is 1: 1.

(2) Pouring the powder ground and mixed in the step (1) into a kneader, adding 1kg of water, 0.75kg of asphalt and 0.05kg of sodium hydroxide solution with the sodium ion concentration of 100mg/L, and kneading for 15 min.

(3) And (3) feeding the kneaded material kneaded in the step (2) into a disc granulator for granulation, controlling the diameter of the spherical particles to be 4-6mm, and airing the spherical particles until the water content is 10% and the compressive strength is 12MPa after the spherical particles are formed.

(4) And (4) carbonizing and activating the ball material treated in the step (3). And (3) feeding the ball material into a carbonization and activation furnace, setting the temperature at 600 ℃, the heating rate at 5 ℃/min and the carbonization time at 1h, and carbonizing in a nitrogen atmosphere. After carbonization, the temperature in the furnace is set to 700 ℃, the heating rate is 10 ℃/min, the activation time is 20min, activation is carried out in the atmosphere consisting of nitrogen and water vapor, and the injection amount of the water vapor is 5.0mL/min/500g of the formed ball material.

(5) And (4) cooling the ball material treated in the step (4) to below 70 ℃, discharging, naturally cooling, sieving to remove powder and fragments, and obtaining a finished product of the coal-based active coke-based ozone catalyst, wherein the number of the finished product is the catalyst A.

Example 2:

(1) weighing and mixing bituminous coal, semi-coke and active components according to the mass ratio of 55:40:0, pouring the mixture into a ball mill, grinding the mixture into fine powder with the particle size of more than 200 meshes, and mixing the fine powder, wherein the total mass is 5 kg.

(2) Pouring the powder ground and mixed in the step (1) into a kneader, adding 1kg of water, 0.75kg of asphalt and 0kg of sodium hydroxide solution with the concentration of 100mg/L, and kneading for 15 min.

(3) The remaining steps were carried out according to the steps (3), (4) and (5) in example 1.

Finally, the coal-made active coke ozone catalyst without active components and auxiliaries is prepared, and the number of the catalyst is the catalyst B.

Example 3

Finally, the coal-made active coke ozone catalyst containing active components and no auxiliaries is prepared, and the number of the catalyst is the catalyst C.

Example 4

(2) Pouring the powder ground and mixed in the step (1) into a kneader, adding 1kg of water, 0.75kg of asphalt and 0.05kg of sodium hydroxide solution with the concentration of 100mg/L, and kneading for 15 min.

Finally, the coal-made active coke ozone catalyst containing no active component and containing the auxiliary agent is prepared, and the number of the catalyst is the catalyst D.

Testing the wastewater treatment performance: the ozone catalysts prepared in examples 1, 2, 3 and 4, and commercially available, industrially used activated carbon-based ozone catalyst HH-27 and silicon aluminum-based catalyst HL-17 were evaluated by a wastewater ozone catalytic oxidation test.

The wastewater treatment conditions are as follows: and selecting the effluent of the secondary sedimentation tank after biochemical treatment in a certain steel plant as the sewage to be treated. The catalysts obtained in examples 1 to 4 and the commercially available catalysts HH-27 and HL-17 and a blank control without catalyst were used for wastewater treatment in a fixed bed reactor, respectively. Through determination, the COD concentration of the coking wastewater is about 150mg/L, the pH value is 7.2-8.5, and the chloride ion concentration is about 3000 mg/L.

The inner diameter of the fixed reaction bed is 10cm, and the overall height is 100 cm; the volume of the wastewater is 3L, and the filling volume of the catalyst is 1.5L; the ozone concentration is 60mg/L, the aeration flow is 0.3L/min, the treatment is continuously carried out for 45min under the condition of room temperature, and the COD removal rate is respectively tested. The COD concentration test method refers to the standard of the dichromate determination of chemical oxygen demand of water (HJ 828 + 2017), each group of test samples tests 3 parallel samples, and the average value is taken. The results are shown in Table 1.

TABLE 1 evaluation test results of coking wastewater treatment performance by different catalysts

Serial number	Condition	45min COD removal (%)
			1	Catalyst free blank control	21.2
2	Example 1 catalyst A	82.3
			3	Example 2 catalyst B	32.7
4	Example 3 catalyst C	62.1
			5	Example 4 catalyst D	27.6
6	Active carbon based catalyst HH-27	64.5
			7	Silicon-aluminium base catalyst HL-17	57.8

As can be seen from table 1:

(1) the test results of the catalysts prepared in the comparative examples 1 to 4 show that the addition of the active component and the auxiliary agent can improve the degradation effect of the catalyst on organic matters, and the analysis reason is probably that the activity, selectivity and stability of the catalyst can be improved and the generation of hydroxyl radicals by ozone catalysis can be promoted by the added active component and the auxiliary agent in the preparation process of the catalyst.

(2) The COD removal rate of the catalyst prepared according to the example 1 is obviously higher than that of commercial catalysts HH-27 and HL-17, which shows that the ozone catalyst of the invention has stronger removal efficiency of refractory organic matters, and the analysis reason is probably that the catalytic specific surface area prepared by the invention is larger, more hydroxyl radicals can be generated by excitation in the same time, and simultaneously, coal is used as a main carrier, so that a certain adsorption effect on the refractory organic matters is generated, the adsorption of the organic matters in water onto the catalyst is accelerated, and the organic matters are reacted with the generated hydroxyl radicals, so that the degradation of the organic matters is accelerated.

And (3) testing the performance of the catalyst: the ozone catalyst prepared in example 1, and commercially available, industrially used activated carbon-based ozone catalyst HH-27 and silicon aluminum-based catalyst HL-17 were subjected to test analysis of indexes such as bulk density, strength, specific surface area, and pore volume.

Measuring the bulk density by adopting a tap density method; measuring the compressive strength of the catalyst by using a strength meter; measuring the specific surface area of the catalyst by adopting a BET method; measuring the total pore volume of the catalyst by adopting a carbon tetrachloride method; the annual attrition rate of the catalyst was determined using an attrition meter.

The test results are shown in Table 2.

TABLE 2 Performance indices of the catalysts

Item	Example 1 catalyst A	Active carbon based catalyst HH-27	Silicon-aluminium base catalyst HL-17
				Specification (mm)	Round spherulite phi 4-6	Round spherulite phi 4-6	Round spherulite phi 6-8
Bulk Density (g/cm)³)	0.50-0.60	0.45-0.55	0.6-0.8
				Compressive Strength (N/grain)	≥100	≥80	≥110
Specific surface area (m)²/g)	1000-1200	1000-1200	≥200
				Total pore volume (cm)³/g)	≥0.50	≥0.50	≥0.40
Annual wear rate	≤2％	≤5％	≤1％

As can be seen from table 2:

(1) the catalyst prepared in example 1 has better compressive strength, lower annual wear rate and longer service life than the commercial activated carbon-based catalyst HH-27.

(2) The catalyst prepared in example 1 has a lower bulk density, and a larger specific surface area and total pore volume than the commercial silicon-aluminum based catalyst HL-17.

In conclusion, the invention uses coal as raw material, which has lower raw material cost than the silicon-aluminum based catalyst; by adopting a blending preparation process, the active components, the auxiliary agent and the carrier are better combined; by adopting the carbonization activation process, the prepared catalyst has higher compressive strength and lower wear rate than the active carbon-based catalyst, and simultaneously has larger specific surface area, adsorption performance and adsorption capacity.

When the ozone is used for catalyzing, oxidizing and degrading organic matters in the sewage, more organic matters can be adsorbed to the surface of the catalyst, the larger specific surface area can promote more hydroxyl radicals to be generated, the degradation of pollutants is accelerated, and the catalytic oxidation efficiency is higher.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. a preparation method of coal-based active coke-based ozone catalyst, is characterized in that: comprise the following steps:

(1) Grinding: the raw coal, blue charcoal and active components are weighed according to the mass ratio of (30-75): (20-60): (5-10), ground into fine powder and mixed; The components are any two or more mixtures of manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide and cerium oxide;

(2) stirring and kneading: adding water, binder and auxiliary agent to the powder that has been ground and mixed in step (1) for stirring and kneading, and the amount of water added accounts for 10-25% of the mass of the powder. The addition amount of the binder accounts for 10-30% of the mass of the powder, and the addition of the auxiliary agent accounts for 0.1-5% of the mass of the powder;

The auxiliary agent is an alkaline solution containing one or more metal ions;

(3) molding: the kneaded material kneaded in step (2) is molded, and the obtained molded body is aired or dried to a moisture content of 5-15%;

(4) carbonization activation: the molding material in step (3) is carbonized and activated;

(5) Cooling and screening: the catalyst that has been carbonized and activated in step (4) is naturally cooled, and then the powder and fragments are removed by sieving to obtain a finished catalyst.

2. the preparation method of coal-based active coke-based ozone catalyst according to claim 1, is characterized in that: in step (1), described raw coal is bituminous coal, anthracite; The particle diameter of described fine powder is 200 meshes Above; when the active components are any two of manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, and cerium oxide, the mass ratio of the two is (1-5): (1-5).

3. the preparation method of coal-based active coke-based ozone catalyst according to claim 1, is characterized in that: in step (2), described binder is one or more in coal tar, pitch, glycerol ; Described metal ion includes potassium, sodium, magnesium; Described alkaline solution total metal ion solubility is 100-1000mg/L.

4. the preparation method of coal-based active coke-based ozone catalyst according to claim 1, is characterized in that: in step (2), described auxiliary agent is sodium hydroxide aqueous solution or potassium hydroxide aqueous solution or sodium hydroxide and A mixed aqueous solution of potassium hydroxide.

5. The preparation method of coal-based activated coke-based ozone catalyst according to claim 1, characterized in that: in step (2), the kneading time is 10-30min.

6. The preparation method of coal-based activated coke-based ozone catalyst according to claim 1, characterized in that: step (3) is: granulating the kneaded material in a disc granulator into spherical granules.

7. The preparation method of coal-based activated coke-based ozone catalyst according to claim 1, characterized in that: step (4) carbonization activation is: firstly heating the carbonization activation device, and after reaching a predetermined temperature, carbonization of the molding material occurs After the reaction is maintained for a period of time, the temperature is raised again to activate the molding material; the carbonization is carried out in a non-oxidative atmosphere; the activation is carried out in an atmosphere composed of a non-oxidative atmosphere and water vapor.

8. The preparation method of coal-based activated coke-based ozone catalyst according to claim 7, characterized in that: the carbonization heating rate is controlled at 5-20 ℃/min, the carbonization reaction temperature is 500-800 ℃, and the carbonization reaction The time is 0.5-3h; the activation temperature rate is controlled at 5-20°C/min, the activation reaction temperature is 500-900°C, and the activation reaction time is 10-120min. In an atmosphere composed of a non-oxidizing atmosphere and water vapor, The injection amount of water vapor is 5.0-20mL/min/500g molding material.

9. A coal-based activated coke-based ozone catalyst, characterized in that: obtained by the preparation method of any one of claims 1-8.

10. Application of the coal-based activated coke-based ozone catalyst of claim 9 in the treatment of coking wastewater.