阅读说明：本技术 一种抗Cl盐的湿式氧化催化剂及其制备方法和应用 (Cl salt-resistant wet oxidation catalyst and preparation method and application thereof ) 是由 郑育元 陈航宁 郭宗英 许丹丹 于 2019-09-02 设计创作，主要内容包括：本发明涉及一种抗Cl盐的湿式氧化催化剂及其制备方法和应用。所述化催化剂,以重量份数计,其包括如下组分：a)95.0～99.0份钙钛矿型复合氧化物,和掺于其上的b)1.0～5.0份金属活性组分；所述钙钛矿型复合氧化物用A_xB_yO_3表示,其中A元素选自Ce、La和Ca中的任意一种；B元素选自Fe、Co和Ni中的任意一种；x取值范围为0.1～0.5,y取值范围为0.5～0.9,且x+y＝1。利用所述催化剂处理有机含Cl盐的有机废水时,具有催化剂强度强,寿命长的优点。(The invention relates to a wet oxidation catalyst for resisting Cl salt, a preparation method and application thereof. The catalyst comprises the following components in parts by weight: a)95.0 to 99.0 parts of perovskite type composite oxide and b)1.0 to 5.0 parts of metal active component doped on the perovskite type composite oxide; a for the perovskite-type composite oxide x B y O 3 Wherein the element A is selected from any one of Ce, La and Ca; b element is selected from any one of Fe, Co and Ni; the value range of x is 0.1-0.5, the value range of y is 0.5-0.9, and x + y is 1. When the catalyst is used for treating organic wastewater containing Cl salt, the catalyst has the advantages of strong strength and long service life.)

1. A Cl salt resistant wet oxidation catalyst comprising the following components:

a) perovskite type composite oxide, and doped thereon

b) A metal active component;

a for the perovskite-type composite oxide_xB_yO₃Wherein the element A is selected from any one of Ce, La and Ca; b element is selected from any one of Fe, Co and Ni; the value range of x is 0.1-0.5, the value range of y is 0.5-0.9, and x + y is 1;

preferably, the value range of x is 0.1-0.3, the value range of y is 0.7-0.9, and x + y is 1;

preferably, the perovskite type composite oxide accounts for 95.0-99.0 parts by weight, and the metal active component accounts for 1.0-5.0 parts by weight.

2. The catalyst of claim 1, wherein the metal active component is selected from at least one of Ru, Pt, Pd, and Rh.

3. A process for preparing a catalyst as claimed in claim 1 or 2, comprising the steps of:

s1, dissolving the salt of the element A and the salt of the element B to form a mixed solution, then carrying out coprecipitation, and washing, drying and grinding the precipitate to obtain precursor powder;

s2, pre-roasting, cooling and grinding the precursor powder to obtain powder of the perovskite type composite oxide;

s3, mixing the powder of the perovskite type composite oxide with a binder, and obtaining a molded carrier after molding, drying and roasting;

and S4, mixing the formed carrier with a salt solution of the metal active component, drying and reducing to obtain the catalyst.

4. The method according to claim 3, wherein in step S1, the co-precipitation is performed under heating, preferably at a temperature of 70-90 ℃; and/or the pH value in the coprecipitation process is 8.5-10.5.

5. The method according to claim 3 or 4, wherein the pre-baking temperature in step S2 is 350-450 ℃.

6. The method according to any one of claims 3 to 5, wherein the powder of the perovskite-type composite oxide has an average particle diameter of 0.5 to 10 μm.

7. The method according to any one of claims 3 to 6, wherein in step S3, the binder is an organic binder and/or an inorganic binder; preferably, the organic binder is selected from any one of PEG, CMC, methylcellulose and starch, and the inorganic binder is selected from any one of nitric acid, aluminum sol and silica sol.

8. The method according to any one of claims 3 to 7, wherein in step S3, the forming method is tablet forming, ball forming or extrusion molding; and/or the roasting temperature is 500-700 ℃, and the roasting time is preferably 3.5-6.0 h; and/or

In the step S4, the reduction temperature is 300-500 ℃, and the reduction time is 3.0-5.5 h.

9. A method for treating organic wastewater containing Cl salt, which comprises contacting organic wastewater containing Cl salt with an oxidant in the presence of the catalyst according to claim 1 or 2 or the catalyst prepared by the method according to any one of claims 3 to 8 to remove COD in the wastewater;

preferably, the organic wastewater containing Cl salt has a Cl salt content of 5 wt% -20 wt% and a COD of 20000-80000 mg/L.

10. The method of claim 9, wherein the oxidant is oxygen or air; and/or the reaction temperature is 220-300 ℃, and the reaction pressure is 5.0-10.0 MPa.

Technical Field

The invention belongs to the field of wastewater treatment, and particularly relates to a Cl salt resistant wet oxidation catalyst, and a preparation method and application thereof.

Background

Catalytic wet oxidation is a method for efficiently treating organic wastewater under the conditions of high temperature and high pressure. In recent years, with the increasing of the pressure of energy conservation and consumption reduction, the environmental protection control becomes stricter and stricter, and the catalytic wet oxidation has higher and higher application value as a chip technology for treating high-concentration organic wastewater. Industrial organic waste water inevitably contains salts, especially Cl salts, which are widely regarded as having different effects on the activity and strength of the catalyst when the salt content is greater than 5%. Therefore, the development of salt-resistant catalysts is imperative.

The catalytic wet oxidation technology is classified into homogeneous and heterogeneous catalytic wet oxidation according to the properties of the catalyst. Early studies focused primarily on homogeneous catalysts, but this process was phased out because of the secondary pollution caused by the catalyst dissolving in the waste, requiring subsequent treatment. In recent years, heterogeneous catalysts have become a focus of research, and mainly include two main types of noble metals and metal oxides, most of which are made of TiO₂、Al₂O₃、SiO₂、ZrO₂Or a composite oxide thereof as a carrier, and an excess element such as Cu, Co, Mn, Fe, Ni or the like or a noble metal element such as Ru, Pt, Pd, Rh or the like is supported on the carrier. However, the two types of catalysts in the prior art have good effects when used for treating simulated organic wastewater without salt, but when used for treating real industrial organic wastewater containing salt, the catalyst strength is rapidly reduced, so that the catalytic activity is rapidly deteriorated.

The following patents are published for catalytic wet oxidation technology:

CN101844827B discloses a catalyst for degrading high-concentration formaldehyde pollutants, which is prepared by loading transition metal components (one of Cu, Ni, Fe, Mn, Co and Zn) and rare earth elements on AlO₂、SiO₂Or TiO₂The preparation technology of the impregnation method is adopted. CN101219376B discloses a catalyst for treating waste water, which is prepared from gamma-Al₂O₃Mn metal oxide as a carrier, Sn metal oxide as a main active component and Sb oxide as an auxiliary agent. CN101485987B belongs to the field of water treatment technology and environmental functional materials, and the catalyst is prepared by taking powdered zinc-aluminum hydrotalcite as a carrier, Fe as an active component and Ce and Ti as promoters by a layered impregnation method.

Disclosure of Invention

Aiming at the problems of weak strength and short service life of a catalyst for treating organic wastewater containing Cl salt in the prior art, the invention provides a novel wet oxidation catalyst for resisting Cl salt.

To this end, the present invention provides in a first aspect a Cl salt resistant wet oxidation catalyst comprising the following components:

a) a perovskite-type composite oxide, and b) a metal active component doped thereon;

a for the perovskite-type composite oxide_xB_yO₃Wherein the element A is selected from any one of Ce, La and Ca; b element is selected from any one of Fe, Co and Ni; the value range of x is 0.1-0.5, the value range of y is 0.5-0.9, and x + y is 1.

In some preferred embodiments of the present invention, x is in a range of 0.1 to 0.3, y is in a range of 0.7 to 0.9, and x + y is 1.

In other preferred embodiments of the present invention, the perovskite-type composite oxide is 95.0 to 99.0 parts by weight, and the metal active component is 1.0 to 5.0 parts by weight.

In some embodiments of the invention, the metal active component is selected from at least one of Ru, Pt, Pd and Rh. Preferably, the metal active component is Ru or Pt.

In some embodiments of the invention, the catalyst has a strength of 80 to 100N.

The second invention of the present invention provides a method for preparing the catalyst according to the first aspect of the present invention, which comprises the steps of:

s1, dissolving the salt of the element A and the salt of the element B to form a mixed solution, then carrying out coprecipitation, and washing, drying and grinding the precipitate to obtain precursor powder;

s2, pre-roasting, cooling and grinding the precursor powder to obtain powder of the perovskite type composite oxide;

s3, mixing the powder of the perovskite type composite oxide with a binder, and obtaining a molded carrier after molding, drying and roasting;

and S4, mixing the formed carrier with a salt solution of the metal active component, drying and reducing to obtain the catalyst.

The salt of the element a and the element B is not particularly limited in the present invention, and for example, the salt of the element a and the element B may be a nitrate, a sulfate, or the like of the element a and the element B.

In some embodiments of the present invention, in step S1, the co-precipitation is performed under heating, preferably at a temperature of 70 to 90 ℃; and/or the pH value in the coprecipitation process is 8.5-10.5.

In some embodiments of the present invention, in step S2, the pre-baking temperature is 350-450 ℃.

In another embodiment of the present invention, the powder of the perovskite-type composite oxide has an average particle diameter of 0.5 to 10 μm. The finer the powder, the more uniformly it is subsequently mixed with the salt solution of the metal active component.

In some embodiments of the present invention, in step S3, the binder is an organic binder and/or an inorganic binder; preferably, the organic binder is selected from any one of PEG, CMC, methylcellulose and starch, and the inorganic binder is selected from any one of nitric acid, aluminum sol and silica sol.

The method of molding the carrier of the present invention is not particularly limited, and in some embodiments of the present invention, the molding method is tablet molding, roll ball molding or extrusion molding.

In some embodiments of the invention, in the step S3, the baking temperature is 500 to 700 ℃, and the baking time is preferably 3.5 to 6.0 hours.

In other embodiments of the present invention, in step S4, the temperature of the reduction is 300 to 500 ℃, and the time of the reduction is 3.0 to 5.5 hours.

In a third aspect, the invention provides a method for treating organic wastewater containing Cl salt, which comprises the step of carrying out contact reaction on the organic wastewater containing Cl salt and an oxidant in the presence of the catalyst according to the first aspect or the catalyst prepared by the method according to the second aspect to remove COD in the wastewater.

The source of the organic wastewater containing Cl salt is not specifically limited in the present invention, and for example, it may be landfill leachate or dye wastewater.

In some embodiments of the invention, the organic wastewater containing Cl salt has a Cl salt content of 5 wt% to 20 wt% and a COD of 20000 to 80000 mg/L. In some embodiments of the invention, the mass space velocity of the organic wastewater containing Cl salt can be 0.4-1.2 h^-1。

In some embodiments of the invention, the oxidant is an oxygen-containing agent, preferably oxygen or air. The volume ratio of oxygen in the oxygen-containing oxygen agent to the organic wastewater can be 50-400.

In other embodiments of the present invention, the temperature of the reaction is 220 to 300 ℃, and the pressure of the reaction is 5.0 to 10.0 MPa.

The evaluation method of the catalyst of the present invention is as follows: 100g of catalyst was taken and charged into a wet oxidation reactor (reactor was a fixed bed reactor, inner diameter was 22mm, reactor length was 700mm), landfill leachate (COD: 25000mg/l, Cl salt content: 15 wt%) and dye wastewater (COD: 35000mg/l, Cl salt content: 10 wt%) were used as raw materials, mixed with oxygen, and passed through the wet oxidation reactor charged with the catalyst. The reaction temperature is 250 ℃, the reaction pressure is 6.5MPa, the volume ratio of oxygen to industrial wastewater (landfill leachate and dye wastewater) is 200, and the mass space velocity of the industrial wastewater is 0.8h^-1. The reaction product was subjected to COD analysis by a Hach COD analyzer to determine the COD value. Time as an indicator of stability, the longer the time, the catalystThe more stable. The strength is used as an index of catalyst strength, and a larger value indicates a stronger catalyst strength.

By adopting the technical scheme of the invention, the industrial wastewater and oxygen are mixed and then pass through a wet oxidation reactor filled with a catalyst, the catalyst comprises 2 parts of noble metal elements (active components) and 98 parts of perovskite type composite oxides (carriers) in parts by weight, and under the conditions that the reaction temperature is 250 ℃, the reaction pressure is 6.5MPa, and the volume ratio of the oxygen to the industrial wastewater is 200, after the reaction is carried out for 1000 hours, the COD removal rate is up to 98.6%, the catalyst strength is up to 95N, and a better technical effect is obtained.

Detailed Description

In order that the present invention may be more readily understood, the following detailed description will proceed with reference being made to examples, which are intended to be illustrative only and are not intended to limit the scope of the invention. The starting materials or components used in the present invention may be commercially or conventionally prepared unless otherwise specified.

Example 1

1. Preparation of perovskite-type composite oxide

Nitrate containing La and Fe (in a molar ratio of 0.2:0.8) was dissolved to prepare a mixed solution, which was heated to 85 ℃ and then added dropwise with sodium carbonate solution under stirring, followed by coprecipitation at pH 9.5 for 2 hours. And cooling, and carrying out suction filtration, washing, drying and grinding on the precipitate to obtain precursor powder. Pre-roasting the precursor powder at 400 ℃ for 2h, cooling and grinding to obtain the perovskite type composite oxide La_0.2Fe_0.8O₃The powder of (4). Adding 98 parts by weight of La_0.2Fe_0.8O₃The powder is put into a kneader to be mixed, 2.4 parts by weight of methylcellulose and 80 parts by weight of water are poured, kneaded, extruded into strips, rolled ball shaped, dried at 100 ℃ for 12h, and then roasted at 600 ℃ for 4.3h to obtain the perovskite type composite oxide spherical carrier with the diameter of 3 mm.

2. Catalyst preparation

RuCl containing 2 parts by weight of Ru₃The aqueous solution is dipped on 98 weight portions of perovskite type composite oxide spherical carrier, and is stood for 4 hours at room temperature and then is at 110 DEG CThe catalyst is dried for 16h in an oven, and then reduced for 4.5h in a tubular atmosphere furnace at 450 ℃ to obtain the catalyst.

3. Catalyst evaluation

100g of the catalyst was charged into a wet oxidation fixed bed reactor and reacted. The reaction temperature is 250 ℃, the reaction pressure is 6.5MPa, the volume ratio of oxygen to industrial wastewater (landfill leachate and dye wastewater) is 200, and the mass space velocity of the industrial wastewater is 0.8h^-1. The reaction product was subjected to COD analysis by a Hach COD analyzer to determine the COD value.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 2

A perovskite type composite oxide was prepared in the same manner as in example 1, except that a nitrate containing La and Fe (in a molar ratio of 0.1:0.9) was dissolved to prepare a mixed solution.

The catalyst preparation and catalyst evaluation were the same as in example 1.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 3

A perovskite type composite oxide was prepared in the same manner as in example 1, except that a mixed solution was prepared by dissolving nitrates containing La and Fe (in a molar ratio of 0.3: 0.7).

The catalyst preparation and catalyst evaluation were the same as in example 1.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 4

1. Preparation of perovskite type composite oxide

Nitrate containing La and Fe (in a molar ratio of 0.2:0.8) was dissolved to prepare a mixed solution, which was heated to 85 ℃ and then added dropwise with sodium carbonate solution under stirring, followed by coprecipitation at pH 9.5 for 2 hours. And cooling, and carrying out suction filtration, washing, drying and grinding on the precipitate to obtain precursor powder. Pre-roasting the precursor powder at 400 ℃ for 2h, cooling and grinding to obtain the perovskite type composite oxide La_0.2Fe_0.8O₃The powder of (4). Adding 98 parts by weight of La_0.2Fe_0.8O₃Powder of (2)Putting the powder into a kneader to mix, pouring 2.4 parts by weight of methylcellulose and 80 parts by weight of water, kneading, extruding into strips, rolling ball forming, drying at 100 ℃ for 12h, and roasting at 600 ℃ for 4.3h to obtain the perovskite type composite oxide spherical carrier with the diameter of 3 mm.

2. Catalyst preparation

Adding H containing 2 parts by weight of Pt₂PtCl₆The aqueous solution is soaked on a perovskite type composite oxide spherical carrier of 98 parts by weight, kept stand for 4h at room temperature, dried for 16h in a drying oven of 110 ℃, and reduced for 4.5h at 450 ℃ in a tubular atmosphere furnace to obtain the catalyst.

3. Catalyst evaluation

100g of the catalyst was charged into a wet oxidation fixed bed reactor and reacted. The reaction temperature is 250 ℃, the reaction pressure is 6.5MPa, the volume ratio of oxygen to industrial wastewater (landfill leachate and dye wastewater) is 200, and the mass space velocity of the industrial wastewater is 0.8h^-1. The reaction product was subjected to COD analysis by a Hach COD analyzer to determine the COD value.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 5

A perovskite type composite oxide was prepared in the same manner as in example 4, except that a mixed solution was prepared by dissolving nitrates containing La and Fe (in a molar ratio of 0.1: 0.9).

The catalyst preparation and catalyst evaluation were the same as in example 4.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 6

A perovskite type composite oxide was prepared in the same manner as in example 4, except that a mixed solution was prepared by dissolving nitrates containing La and Fe (in a molar ratio of 0.3: 0.7).

The catalyst preparation and catalyst evaluation were the same as in example 4.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 7

The perovskite-type composite oxide was prepared and the catalyst was evaluated in the same manner as in example 1.

The catalyst was prepared as in example 1, except that RuCl containing 1 part by weight of Ru₃The aqueous solution is impregnated on 99 parts by weight of a perovskite type composite oxide spherical carrier.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 8

The perovskite-type composite oxide was prepared and the catalyst was evaluated in the same manner as in example 1.

The catalyst was prepared as in example 1, except that RuCl containing 3 parts by weight of Ru₃The aqueous solution was impregnated on 97 parts by weight of a perovskite type composite oxide spherical carrier.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 9

1. Preparation of perovskite type composite oxide

Nitrate containing Ce and Ni (in a molar ratio of 0.2:0.8) was dissolved to prepare a mixed solution, which was heated to 85 ℃, and a sodium carbonate solution was added dropwise with stirring, followed by coprecipitation at PH 9.5 for 2 hours. And cooling, and carrying out suction filtration, washing, drying and grinding on the precipitate to obtain precursor powder. Pre-roasting the precursor powder at 400 ℃ for 2h, cooling and grinding to obtain the perovskite type composite oxide Ce_0.2Ni_0.8O₃The powder of (4). 98 parts by weight of Ce_0.2Ni_0.8O₃The powder is put into a kneader to be mixed, 2.4 parts by weight of methylcellulose and 80 parts by weight of water are poured, kneaded, extruded into strips, rolled ball shaped, dried at 100 ℃ for 12h, and then roasted at 600 ℃ for 4.3h to obtain the perovskite type composite oxide spherical carrier with the diameter of 3 mm.

2. Catalyst preparation

RuCl containing 2 parts by weight of Ru₃The aqueous solution is soaked on a perovskite type composite oxide spherical carrier of 98 parts by weight, kept stand for 4h at room temperature, dried for 16h in a drying oven of 110 ℃, and reduced for 4.5h at 450 ℃ in a tubular atmosphere furnace to obtain the catalyst.

3. Catalyst evaluation

Get and urge100g of the catalyst was charged into a wet oxidation fixed bed reactor and reacted. The reaction temperature is 250 ℃, the reaction pressure is 6.5MPa, the volume ratio of oxygen to industrial wastewater (landfill leachate and dye wastewater) is 200, and the mass space velocity of the industrial wastewater is 0.8h^-1. The reaction product was subjected to COD analysis by a Hach COD analyzer to determine the COD value.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 10

A perovskite type composite oxide was prepared in the same manner as in example 9, except that nitrate containing Ce and Ni (in a molar ratio of 0.1:0.9) was dissolved to prepare a mixed solution.

The catalyst preparation and catalyst evaluation were the same as in example 9.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Example 11

A perovskite type composite oxide was prepared in the same manner as in example 9, except that nitrate containing Ce and Ni (in a molar ratio of 0.3:0.7) was dissolved to prepare a mixed solution.

The catalyst preparation and catalyst evaluation were the same as in example 9.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Comparative example 1

1. Preparation of the support

98 parts by weight of TiO₂The powder (average particle size 20nm) was mixed in a kneader, 3.0 parts by weight of methylcellulose and 90 parts by weight of water were poured, kneaded, extruded, rolled into a ball, dried at 100 ℃ for 12 hours, and then calcined at 650 ℃ in a muffle furnace for 4.5 hours to obtain a spherical carrier having a diameter of 3 mm.

2. Catalyst preparation

RuCl containing 2 parts by weight of Ru₃The aqueous solution is immersed on a spherical carrier of 98 parts by weight, kept stand for 4h at room temperature, dried in an oven of 110 ℃ for 16h, and then reduced in a tubular atmosphere furnace at 450 ℃ for 4.5h to obtain the catalyst.

3. Catalyst evaluation

100g of the catalyst was taken out and charged in a wet systemAnd (4) oxidizing the reaction product in a fixed bed reactor. The reaction temperature is 250 ℃, the pressure is 6.5MPa, the volume ratio of oxygen to industrial wastewater (landfill leachate and dye wastewater) is 200, and the mass space velocity of the industrial wastewater is 0.8h^-1. The COD value of the reaction product was determined using an analyzer from Hach company.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

Comparative example 2

1. Preparation of the support

98 parts by weight of TiO₂The powder (average particle size 20nm) was mixed in a kneader, 3.0 parts by weight of methylcellulose and 90 parts by weight of water were poured, kneaded, extruded, rolled into balls, dried at 100 ℃ for 12 hours, and then calcined at 700 ℃ in a muffle furnace for 4.4 hours to obtain spherical carriers having a diameter of 3 mm.

2. Catalyst preparation

Adding H containing 2 parts by weight of Pt₂PtCl₆The aqueous solution is immersed on a spherical carrier of 98 parts by weight, kept stand for 4h at room temperature, dried in an oven of 110 ℃ for 16h, and then reduced in a tubular atmosphere furnace at 450 ℃ for 4.5h to obtain the catalyst.

3. Catalyst evaluation

100g of the catalyst was charged into a wet oxidation fixed bed reactor and reacted. The reaction temperature is 250 ℃, the pressure is 6.5MPa, the volume ratio of oxygen to industrial wastewater (landfill leachate and dye wastewater) is 200, and the mass space velocity of the industrial wastewater is 0.8h^-1. The COD value of the reaction product was determined using an analyzer from Hach company.

The composition of the catalyst components is shown in Table 1, and the evaluation results of the catalyst are shown in Table 2.

TABLE 1

TABLE 2

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.