Heterogeneous Fenton catalyst prepared from waste phosphorus-containing molecular sieve catalyst, preparation method thereof and application thereof

Abstract

The present invention discloses a heterogeneous Fenton catalyst prepared from a spent phosphorus-containing molecular sieve catalyst, and its preparation method and application. A heterogeneous Fenton catalyst prepared from a spent phosphorus-containing molecular sieve catalyst includes a pretreated spent phosphorus-containing molecular sieve catalyst and iron oxide supported on the spent phosphorus-containing molecular sieve catalyst. The heterogeneous Fenton catalyst prepared from the spent phosphorus-containing molecular sieve catalyst of the present invention can make full use of the spent phosphorus-containing molecular sieve catalyst, turn waste into treasure, and the heterogeneous Fenton catalyst has a high added value and can effectively remove MTBE in water bodies.

Description

Technical Field

[0001] The method of the present invention relates to the field of utilization of waste catalysts. Specifically, the present invention relates to a heterogeneous Fenton catalyst prepared from a phosphorus-containing molecular sieve waste catalyst and a preparation method thereof, and a method for removing MTBE in water bodies. Background Art

[0002] The methanol-to-olefins (MTO) technology refers to the process technology for producing light olefins from methanol, mainly including processes such as methanol catalytic conversion to olefins, separation and purification of products, etc. The conversion reaction of methanol to olefins was first discovered by Mobile in the early 1970s on a ZSM-5 catalyst. Mobile studied the process technology for producing olefins from methanol in a tubular reactor using ZSM-5 molecular sieve as the catalyst. Subsequently, UOP and Norsk Hydro developed the MTO technology. This technology uses methanol as the raw material, adopts a circulating fluidized bed process, and uses the SAPO-34 molecular sieve developed by UOP as the catalyst. The main products of this technology are light olefins such as ethylene, propylene, and butene, and the remaining impurities are relatively few. Since the conversion of methanol to olefins is an exothermic reaction and catalyst deactivation is a rapid process, a fluidized bed reactor can remove the reaction heat in a timely manner and is also convenient for catalyst regeneration. Therefore, compared with a fixed bed, the use of a fluidized bed reactor improves the reaction efficiency.

[0003] MTO catalysts have characteristics such as poor stability and easy deactivation, but their activity can be restored through regeneration means. Therefore, the fluidized bed reaction form is suitable for processes with a high deactivation rate of MTO catalysts and can perform continuous regeneration and cyclic operation of MTO catalysts. Due to the inherent characteristics of the fluidized bed reaction regeneration technology and the diversity of influencing factors in the fluidization process, the intense impact and friction of solid catalysts during the flow process cause the catalysts to accelerate pulverization, and a large amount of fine-grained catalysts are continuously carried out. The catalyst fines adsorb more pollutants such as oils to form hazardous wastes, which will cause harm to the environment if not treated. In addition, the waste MTO catalysts mainly contain elements such as phosphorus, aluminum, and silicon, and the phosphorus content (calculated as P 2 O 5 is up to 10-15% by weight), and direct disposal also causes waste of beneficial resources. Moreover, the current environmental protection policies are becoming increasingly strict, and simple disposal methods such as landfilling are restricted.

[0004] In addition, for wastewater containing methyl tert-butyl ether (MTBE), the traditional homogeneous Fenton system mainly uses ferrous and hydrogen peroxide (Fenton reagent) to remove MTBE in water. Since the traditional homogeneous Fenton system is only effective under acidic conditions and also generates iron sludge, causing secondary pollution, its application in wastewater treatment is greatly limited. Compared with the traditional homogeneous Fenton system, the heterogeneous Fenton system has the advantages of easy separation and recyclability, but it is expensive and its oxidation effect needs to be further improved. Summary of the Invention

[0005] Aiming at the problems existing in the prior art that the waste catalyst of phosphorus-containing molecular sieve cannot be fully utilized, wasting resources and being environmentally unfriendly, and the existing catalysts for removing MTBE in water are expensive and their effects need to be improved, the present invention provides a heterogeneous Fenton catalyst prepared from a waste catalyst of phosphorus-containing molecular sieve, its preparation method and application. The heterogeneous Fenton catalyst prepared from the waste catalyst of phosphorus-containing molecular sieve of the present invention can make full use of the waste catalyst of phosphorus-containing molecular sieve, turning waste into treasure, and this heterogeneous Fenton catalyst has a high added value and can effectively remove MTBE in water. In addition, the preparation process of the heterogeneous Fenton catalyst of the present invention is simple.

[0006] The first aspect of the present invention provides a heterogeneous Fenton catalyst prepared from a waste catalyst of phosphorus-containing molecular sieve, which comprises a pretreated waste catalyst of phosphorus-containing molecular sieve and iron oxide supported on the waste catalyst of phosphorus-containing molecular sieve.

[0007] In the above technical solution, preferably, the molar ratio of the iron oxide to the waste catalyst of phosphorus-containing molecular sieve is 0.3 - 1.1:1, preferably 0.5 - 1:1, more preferably 0.5 - 0.9:1, wherein the iron oxide is calculated as iron element, and the waste catalyst of phosphorus-containing molecular sieve is calculated as phosphorus element.

[0008] In the above technical solution, preferably, the conditions of the pretreatment include: the temperature is 500 - 1000 °C, preferably 600 - 700 °C, and the time is 4 - 36 h, preferably 5 - 12 h.

[0009] In the above technical solution, preferably, the organic matter residue of the pretreated waste catalyst of phosphorus-containing molecular sieve does not exceed 0.3% by weight.

[0010] In the above technical solution, preferably, the waste catalyst of phosphorus-containing molecular sieve is an MTO waste catalyst, preferably a SAPO-34 molecular sieve.

[0011] In the above technical solution, more preferably, the waste catalyst of phosphorus-containing molecular sieve is made of molecular sieve, clay and binder.

[0012] In the above technical solution, more preferably, in the phosphorus-containing molecular sieve waste catalyst, the phosphorus content calculated as P 2 O 5 is 8-20% by weight, preferably 10-15% by weight.

[0013] In the second aspect of the present invention, a method for preparing a heterogeneous Fenton catalyst using a phosphorus-containing molecular sieve waste catalyst is provided, including:

[0014] (1) Pretreating the phosphorus-containing molecular sieve waste catalyst to obtain a first material;

[0015] (2) Loading the first material with an additive containing an iron salt to obtain a second material;

[0016] (3) Drying and calcining the second material.

[0017] In the above technical solution, preferably, the residual amount of organic matter in the first material does not exceed 0.3% by weight.

[0018] In the above technical solution, preferably, the conditions of the pretreatment include: the temperature is 500-1000 °C, preferably 600-700 °C, and the time is 4-36 h, preferably 5-12 h.

[0019] In the above technical solution, preferably, the iron salt is selected from one or more of ferric sulfate, ferric nitrate, ferric citrate, ferric chloride, and ferric acetate. In the present invention, the iron salt can be in the form of an iron salt and / or a hydrate of an iron salt. Both can be obtained through commercial purchase.

[0020] In the above technical solution, the additive containing an iron salt can contain only an iron salt, or pseudo-boehmite, nitric acid solution, etc. can be added as needed.

[0021] In the above technical solution, preferably, the molar ratio of the additive to the first material is 0.3-1.1:1, preferably 0.5-1:1, more preferably 0.5-0.9:1, wherein the additive is calculated as iron element and the first material is calculated as phosphorus element.

[0022] In the above technical solution, preferably, the loading method includes one or more of kneading loading, impregnation loading, and high-energy ball milling loading.

[0023] In the above technical solution, preferably, the conditions of the calcination include: the temperature is 400-800 °C, preferably 500-600 °C, and the calcination time is 3-12 h, preferably 4-8 h.

[0024] In the above technical solution, the conditions of the drying have a relatively wide selection range for the purpose of being able to remove moisture.

[0025] The third aspect of the present invention provides a method for removing MTBE from water body, which comprises contacting the water body containing MTBE with the heterogeneous Fenton catalyst described above or the heterogeneous Fenton catalyst prepared according to the method described above.

[0026] In the above technical solution, preferably, hydrogen peroxide is also used during the contact.

[0027] In the present invention, the dosage ratio of the heterogeneous Fenton catalyst to hydrogen peroxide has a relatively wide selection range and can be determined according to needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the process flow diagram of Embodiment 1 of the present invention.

[0029] The present invention will be further described below through examples, but the content of the present invention is not limited. DETAILED DESCRIPTION OF THE INVENTION

[0030] To make the present invention easier to understand, the present invention will be described in detail below in conjunction with examples. These examples are only illustrative and are not limited to the application scope of the present invention.

[0031] In the present invention, since MTBE is a carbon-containing organic compound, the method for detecting the MTBE removal rate is the TOC (total organic carbon) removal rate. In the following examples and comparative examples, the TOC of the solution is measured by a total organic carbon analyzer (TOC-L CPH / CPN , Shimadzu).

[0032] TOC removal rate = (reduced TOC in the solution / initial TOC) × 100%.

[0033]

Example 1

[0034] This example is used to illustrate the heterogeneous Fenton catalyst prepared from the waste catalyst of phosphorus-containing molecular sieve and its preparation method of the present invention. The process flow diagram is as Figure 1 shown.

[0035] (1) Put the waste catalyst raw material of phosphorus-containing molecular sieve (dry basis after removing organic matter, Al 2 O 3 is 69.36% by weight, SiO 2 is 18.21% by weight, P 2 O 5 is 11.65% by weight) into an industrial electric furnace, and treat it at 700 °C for 8 h to obtain a material, and the residual amount of organic matter is 0.22% by weight.

[0036] (2) Take 700 g of the material obtained in step (1), add 464 g of iron(III) nitrate nonahydrate, 400 g of pseudo-boehmite, and 600 mL of 1.5 wt% nitric acid solution, knead and extrude into strips, and air-dry naturally. The molar ratio of total iron (calculated as iron element) to total phosphorus (calculated as phosphorus element) in the obtained product is 1:1.

[0037] (3) Dry the solid obtained in step (2) at 90 °C for 24 h, and then calcine it at 550 °C for 6 h in an air atmosphere to obtain a heterogeneous Fenton catalyst product.

[0038]

Example 2

[0039] This example is used to illustrate the heterogeneous Fenton catalyst prepared from a phosphorus-containing molecular sieve waste catalyst and its preparation method according to the present invention.

[0040] (1) Put the phosphorus-containing molecular sieve waste catalyst raw material (in the dry basis after removing organic matter, Al 2 O 3 is 69.36 wt%, SiO 2 is 18.21 wt%, P 2 O 5 is 11.65 wt%) into an industrial electric furnace, and treat it at 500 °C for 4 h to obtain a material, and the residual amount of organic matter is 0.29 wt%.

[0041] (2) Take 700 g of the material obtained in step (1), impregnate it with 115 g of ferric sulfate in an equal volume manner, and the molar ratio of total iron (calculated as iron element) to total phosphorus (calculated as phosphorus element) in the obtained product is 0.5:1.

[0042] (3) Dry the solid obtained in step (2) at 90 °C for 24 h, and then calcine it at 550 °C for 6 h in an air atmosphere to obtain a heterogeneous Fenton catalyst product.

[0043]

Example 3

[0044] This example is used to illustrate the heterogeneous Fenton catalyst prepared from a phosphorus-containing molecular sieve waste catalyst and its preparation method according to the present invention.

[0045] (1) Put the phosphorus-containing molecular sieve waste catalyst raw material (in the dry basis after removing organic matter, Al 2 O 3 is 69.36 wt%, SiO 2 is 18.21 wt%, P 2 O 5 is 11.65 wt%) into an industrial electric furnace, and treat it at 1000 °C for 36 h to obtain a material, and the residual amount of organic matter is 0.03 wt%.

[0046] (2) Take 700 g of the material obtained in step (1) and 510 g of ferric nitrate nonahydrate and put them into a planetary ball mill. Rotate at 800 rpm for 5 h to obtain a product with a molar ratio of total iron (calculated as iron element) to total phosphorus (calculated as phosphorus element) of 1.1:1;

[0047] (3) Dry the solid obtained in step (2) at 90 °C for 24 h, and then calcine it at 550 °C for 6 h in an air atmosphere to obtain a heterogeneous Fenton catalyst product.

[0048]

Example 4

[0049] This example is used to illustrate the heterogeneous Fenton catalyst prepared from a phosphorus-containing molecular sieve waste catalyst and its preparation method of the present invention.

[0050] According to the method of Example 1, the only difference is that the addition amount of ferric nitrate nonahydrate is changed to make the molar ratio of total iron (calculated as iron element) to total phosphorus (calculated as phosphorus element) of the obtained product 0.9:1. Finally, a heterogeneous Fenton catalyst product is obtained.

[0051]

Comparative Example 1

[0052] (1) Take 700 g of the raw material of the phosphorus-containing molecular sieve waste catalyst without pretreatment, add 464 g of ferric nitrate nonahydrate, 400 g of pseudo-boehmite, and 600 mL of 1.5 wt% nitric acid solution, knead and extrude, and air dry. The molar ratio of total iron (calculated as iron element) to total phosphorus (calculated as phosphorus element) of the obtained product is 1:1.

[0053] (2) Dry the solid obtained in step (1) at 90 °C for 24 h, and then calcine it at 550 °C for 6 h in an air atmosphere to obtain a heterogeneous Fenton catalyst product.

[0054]

Comparative Example 2

[0055] (1) Put the raw material of the phosphorus-containing molecular sieve waste catalyst (in the dry basis after removing organic matter, Al 2 O 3 is 69.36 wt%, SiO 2 is 18.21 wt%, P 2 O 5 is 11.65 wt%) into an industrial electric furnace and treat it at 700 °C for 8 h to obtain a material with an organic matter residue of 0.22 wt%.

[0056] (2) Take 700 g of the material obtained in step (1), add 400 g of pseudo-boehmite, and 600 mL of 1.5 wt% nitric acid solution, knead and extrude, and air dry. The molar ratio of total iron (calculated as iron element) to total phosphorus (calculated as phosphorus element) of the obtained product is 0:1.

[0057] (3) The solid obtained in step (2) is dried at 90 °C for 24 h and then calcined at 550 °C for 6 h in an air atmosphere to obtain a heterogeneous Fenton catalyst product.

[0058]

Comparative Example 3

[0059] The method of Example 1 was used, except that the phosphorus-containing molecular sieve waste catalyst raw material was replaced with a waste NaX molecular sieve catalyst with a FAU framework structure (based on the total weight of the waste molecular sieve catalyst, in parts by weight, the content of Al 2 O 3 was 30 parts, the content of SiO 2 was 48 parts, the content of P 2 O 5 was 0 part, and the total content of Na 2 O, K 2 O, MgO and CaO was 8 parts, and the carbon deposition amount was 5 parts).

[0060] Finally, a catalyst product was obtained.

[0061]

Comparative Example 4

[0062] The method of Example 1 was used, except that ferric nitrate nonahydrate was replaced with copper sulfate pentahydrate.

[0063] Finally, a catalyst product was obtained.

[0064]

Comparative Example 5

[0065] (1) 700 g of fresh SAPO-34 catalyst was taken and impregnated with 464 g of ferric nitrate nonahydrate (2 mol / L) solution for 24 h.

[0066] (2) The solid obtained in step (1) was dried at 90 °C for 24 h and then calcined at 550 °C for 6 h in an air atmosphere to obtain a heterogeneous Fenton catalyst product.

[0067]

Test Example 1

[0068] The performance evaluation of the Fenton catalyst was carried out on a fluidized bed device. The experimental conditions were as follows: the simulated organic wastewater was a solution containing MTBE, the concentration of MTBE in the raw water was about 0.5 g / L, the initial TOC concentration was 200 ppm, hydrogen peroxide was added, and then the heterogeneous Fenton catalysts of Examples 1-4 and Comparative Examples 1-4 were added respectively.

[0069] The reaction temperature was 30 °C, the reaction time was 1 h, the rotation speed was 300 rpm, and the heterogeneous Fenton catalyst based on Fe element and H 2 O 2 was Fe:H 2 O 2= 1:30, MTBE:H 2 O 2 The molar ratio = 1:30. The evaluation results are listed in Table 1.

[0070] Table 1

[0071] Number Molar ratio of total iron to total phosphorus TOC removal rate (%) Example 1 1:1 30 Example 2 0.5:1 40 Example 3 1.1:1 28 Example 4 0.9:1 42 Comparative Example 1 1:1 10 Comparative Example 2 0:1 0.5 Comparative Example 3 0:0 0.1 Comparative Example 4 0:1 0.4

[0072]

Test Example 2

[0073] Calculate the costs of Example 1 and Comparative Example 5 and list them in Table 2.

[0074] Among them, the outsourcing cost for treating the waste catalyst of phosphorus-containing molecular sieve is about 6,000 yuan / ton, ferric nitrate nonahydrate is 5,000 yuan / ton, pseudo-boehmite is 4,000 yuan / ton, and the cost of fresh SAPO-34 catalyst is 100,000 yuan / ton.

[0075] Table 2

[0076] Number Cost (yuan / ton) Example 1 -178.92 Comparative Example 5 62000

[0077] The above are only the preferred examples of the present invention. It should be pointed out that for those of ordinary skill in the art, under the technical inspiration provided by the present invention, as common general knowledge in the art, other equivalent variations and improvements can also be made, which should also be regarded as the protection scope of the present invention.

Claims

1. A heterogeneous Fenton catalyst prepared from a waste phosphorus-containing molecular sieve catalyst, comprising a pretreated waste phosphorus-containing molecular sieve catalyst and iron oxide supported on the waste phosphorus-containing molecular sieve catalyst; The molar ratio of the iron oxide to the waste phosphorus-containing molecular sieve catalyst is 0.3 to 1.1:1, wherein, the iron oxide is calculated based on iron element, and the waste phosphorus-containing molecular sieve catalyst is calculated based on phosphorus element; The conditions of the pretreatment include: temperature is 500 to 1000 °C, and time is 4 to 36 h; In the phosphorus-containing molecular sieve waste catalyst, the phosphorus content calculated as P 2 O 5 is 8-20% by weight.

2. The heterogeneous Fenton catalyst according to claim 1, characterized in that the molar ratio of the iron oxide to the waste phosphorus-containing molecular sieve catalyst is 0.5 to 1:1, wherein the iron oxide is calculated based on iron element, and the waste phosphorus-containing molecular sieve catalyst is calculated based on phosphorus element.

3. The heterogeneous Fenton catalyst according to claim 1, characterized in that The conditions of the pretreatment include: temperature is 600 to 700 °C, and time is 5 to 12 h.

4. The heterogeneous Fenton catalyst according to any one of claims 1-3, characterized in that the organic matter residue amount of the pretreated waste phosphorus-containing molecular sieve catalyst does not exceed 0.3% by weight; and / or, the waste phosphorus-containing molecular sieve catalyst is an MTO waste catalyst; And / or, in the phosphorus-containing molecular sieve waste catalyst, the phosphorus content calculated as P 2 O 5 is 10 to 15% by weight.

5. The heterogeneous Fenton catalyst according to claim 4, characterized in that the waste phosphorus-containing molecular sieve catalyst is a SAPO-34 molecular sieve.

6. A method for preparing a heterogeneous Fenton catalyst from a waste phosphorus-containing molecular sieve catalyst, comprising: (1) Pretreating the waste phosphorus-containing molecular sieve catalyst to obtain a first material; (2) Loading an additive containing iron salt on the first material to obtain a second material; (3) Drying and calcining the second material; The molar ratio of the additive to the first material is 0.3 to 1.1:1, wherein the additive is calculated based on iron element, and the first material is calculated based on phosphorus element; The conditions of the pretreatment include: temperature is 500 to 1000 °C, and time is 4 to 36 h; In the phosphorus-containing molecular sieve waste catalyst, the phosphorus content calculated as P 2 O 5 is 8-20% by weight.

7. The method according to claim 6, characterized in that the organic matter residue amount in the first material does not exceed 0.3% by weight; and / or, the conditions of the pretreatment include: temperature is 600 to 700 °C, and time is 5 to 12 h.

8. The method according to claim 6 or 7, characterized in that the iron salt is selected from one or more of ferric sulfate, ferric nitrate, ferric citrate, ferric chloride and ferric acetate.

9. The method according to claim 6 or 7, characterized in that the molar ratio of the additive to the first material is 0.5 to 1:1, wherein the additive is calculated based on iron element, and the first material is calculated based on phosphorus element.

10. The method according to claim 6 or 7, characterized in that the loading method includes one or more of kneading loading, impregnation loading and high-energy ball milling loading; and / or, the conditions of the calcination include: temperature is 400 to 800 °C, and the calcination time is 3 to 12 h.

11. The method according to claim 10, characterized in that The calcination conditions include: the temperature is 500-600°C, and the calcination time is 4-8 h.

12. A method for removing MTBE from water characterized in that the water containing MTBE is contacted with the heterogeneous Fenton catalyst described in any one of claims 1-5 or the heterogeneous Fenton catalyst prepared by the method described in any one of claims 6-11; hydrogen peroxide is also used during the contact.

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