Preparation method of heterogeneous Fenton catalyst, catalyst obtained and application

Abstract

This invention discloses a method for preparing a heterogeneous Fenton catalyst, the resulting catalyst, and its applications. The method for preparing the heterogeneous Fenton catalyst includes the following steps: (1) ammonium leaching treatment of iron-containing waste catalyst after high-temperature calcination to obtain a leachate and a leaching residue; (2) optionally, treating the leaching residue obtained in step (1) with a Fe leaching agent to obtain a catalyst precursor; (3) mixing the leaching residue obtained in step (1) or the catalyst precursor obtained in step (2) with additives and polyoxometalates, molding, drying, and calcining to obtain the heterogeneous Fenton catalyst. This invention utilizes an iron-containing waste catalyst to prepare a heterogeneous Fenton catalyst. The preparation process is simple, not only making full use of the iron-containing waste catalyst, saving resources, and benefiting environmental protection, but also producing a heterogeneous Fenton catalyst with high added value, effectively removing organic matter such as phenol from water.

Description

Technical Field

[0001] This invention relates to the technical field of waste catalyst utilization, specifically, to a method for preparing a heterogeneous Fenton catalyst, the resulting catalyst, and its applications. Background Technology

[0002] Styrene is a crucial basic organic monomer in petrochemical production and an important organic raw material for the production of plastics and synthetic rubber. In 2020, China's styrene production capacity was approximately 12.22 million tons, a 29% increase year-on-year, while output reached 9.9 million tons, a 24% increase year-on-year, and apparent consumption reached approximately 12.78 million tons. The industrial plant for ethylbenzene dehydrogenation to styrene is large-scale, requiring a significant amount of catalyst, typically replaced every two years. Analysis of the catalyst loading volume at Chinese styrene manufacturers shows that the catalyst loading volume accounts for 0.1% of styrene production capacity. With the increase in styrene production capacity in recent years, the catalyst loading volume for ethylbenzene dehydrogenation has also increased accordingly. In 2015, China's catalyst loading volume was 5.0 kt, reaching 9.9 kt in 2020, with an average annual growth rate of 15%. As the demand for catalyst continues to increase, the amount of waste catalyst is also rising. Based on the composition of ethylbenzene dehydrogenation catalysts, which contain 61–84% Fe₂O₃, 7–14% K₂O, and 6–14% CeO₂, they represent valuable metal resources. However, no technologies for the recycling and utilization of ethylbenzene dehydrogenation catalysts have been reported. Developing resource utilization technologies for waste ethylbenzene dehydrogenation catalysts has the dual significance of achieving economic value-added and environmental protection.

[0003] Furthermore, for wastewater containing phenol, the traditional homogeneous Fenton system mainly uses ferrous sulfate and hydrogen peroxide (Fenton's reagent) to remove phenol from the water. However, the traditional homogeneous Fenton system is only effective under acidic conditions and also produces iron sludge, causing secondary pollution, which greatly limits its application in wastewater treatment (Nishanth Thomas, Dionysios D. Dionysiou, Suresh C. Pillai. Heterogeneous Fenton Catalysts: A Review of Recent Advances. Journal of Hazardous Materials, (2020)). Compared with the traditional homogeneous Fenton system, the heterogeneous Fenton system has advantages such as easy separation and recyclability, but it is expensive, and its oxidation effect needs further improvement. Summary of the Invention

[0004] To address the problems of low utilization rate of iron-containing waste catalysts, resulting in resource waste and environmental pollution, and the high cost and limited effectiveness of existing heterogeneous Fenton catalyst systems in catalytic degradation of organic matter, this invention provides a method for preparing a heterogeneous Fenton catalyst, the resulting catalyst, and its applications. This invention utilizes an iron-containing waste catalyst to prepare a heterogeneous Fenton catalyst. The preparation process is simple, fully utilizes the iron-containing waste catalyst, saves resources, and benefits environmental protection. Furthermore, the prepared heterogeneous Fenton catalyst has high added value and can effectively remove organic matter such as phenol from water.

[0005] This invention provides a method for preparing a heterogeneous Fenton catalyst, comprising the following steps:

[0006] (1) The iron-containing waste catalyst after high-temperature roasting is subjected to ammonium leaching treatment to obtain leachate and leaching residue;

[0007] (2) Optionally, the leaching residue obtained in step (1) is treated with Fe leaching agent to obtain a catalyst precursor;

[0008] (3) The leaching residue obtained in step (1) or the catalyst precursor obtained in step (2) is mixed with additives and polyoxometalates, shaped, dried and calcined to obtain the heterogeneous Fenton catalyst.

[0009] In the above technical solution, step (1) involves the use of waste styrene catalyst, which is derived from waste styrene catalyst. The waste styrene catalyst contains Fe, Ce and K. The waste styrene catalyst also contains at least one of Mg, Cr, Mo, Ca, Zn and Cu.

[0010] In the above technical solution, step (1), the composition of the iron-containing waste catalyst, based on the mass of the catalyst, includes: Fe content of 40% to 60%, K content of 5% to 12%, Ce content of 4% to 12%, and the total amount of other elements (including at least one of Mg, Cr, Mo, Ca, Zn, and Cu) less than 5%; the molar ratio of Fe to Ce in the iron-containing waste catalyst is 8:1 to 37:1.

[0011] In the above technical solution, in step (1), the conditions of the high-temperature roasting treatment are such that the residual amount of organic matter in the sample does not exceed 0.3% by weight. The treatment conditions are: temperature of 400℃~1000℃, preferably 600℃~800℃, and time of 4h~36h, preferably 5h~12h.

[0012] In the above technical solution, in step (1), the leaching agent used in the ammonium leaching treatment is an NH4-containing leaching agent. +The solution is preferably selected from one or more of ammonia, ammonium chloride, ammonium nitrate, and ammonium carbonate. The concentration of the leaching agent is 0.5 mol / L to 10 mol / L, the reaction temperature is 20℃ to 150℃, the reaction time is 0.5 h to 48 h, and the solid-liquid ratio is 1:3 g / mL to 1:30 g / mL. Preferably, the concentration of the leaching agent is 1 mol / L to 6 mol / L, the reaction temperature is 60℃ to 120℃, the reaction time is 1 h to 3 h, and the solid-liquid ratio is 1:8 g / mL to 1:15 g / mL.

[0013] In the above technical solution, the concentrations of K, Fe, and Ce in the filtrate obtained in step (1) are measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate is defined as the metal content in the filtrate divided by the total mass of metals in the raw material. The leaching rate of K is 50% to 100%, while the leaching rates of Fe and Ce are both less than 5%.

[0014] In the above technical solution, the molar ratio of Fe to Ce in the catalyst precursor obtained in step (2) is adjusted to 8:1 to 20:1. If the molar ratio of Fe to Ce in the leaching residue obtained in step (1) is within this range, Fe leaching is not required.

[0015] In the above technical solution, step (2) uses Fe leaching agents including one or more of hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid. The concentration of hydrogen ions is 0.5 mol / L to 10 mol / L, the reaction temperature is 50℃ to 150℃, the reaction time is 0.5 h to 48 h, and the solid-liquid ratio is 1:3 g / mL to 1:30 g / mL.

[0016] In the above technical solution, the molar ratio of Fe to Ce in the leaching residue obtained in step (3), step (1) or the catalyst precursor obtained in step (2) is 8:1 to 20:1.

[0017] In the above technical solution, step (3) involves an additive comprising molecular sieves, clay, and a binder. The molecular sieve comprises one or more of all-silica molecular sieves, phosphorus-aluminum molecular sieves, and silica-alumina molecular sieves, preferably at least one of β molecular sieves, X molecular sieves, Y molecular sieves, mordenite, MCM-22 molecular sieves, and MCM-41, and is added at a mass of 20% to 50% of the total solid mass; the clay comprises at least one of attapulgite, kaolinite, montmorillonite, and illite, and is added at a mass of 40% to 60% of the total solid mass; the binder comprises at least one of cellulose and guar gum, and is added at a mass of 1% to 10% of the total solid mass; wherein, the total solid mass is the total mass of the leaching residue obtained in step (1) or the catalyst precursor obtained in step (2) mixed with the additives and polyoxometalates.

[0018] In the above technical solution, step (3) involves a polyoxometalate salt of H6P2W9Mo9O. 62 The amount added should account for 1% to 10% of the total solid mass.

[0019] In the above technical solution, step (3) involves drying conditions of 70℃~150℃ and drying time of 12h~72h.

[0020] In the above technical solution, step (3) includes the following calcination conditions: temperature of 400℃~800℃, preferably 500℃~600℃, and calcination time of 3h~12h, preferably 4h~8h.

[0021] A second aspect of the present invention provides a heterogeneous Fenton catalyst obtained by the above preparation method.

[0022] The third aspect of this invention provides the application of the heterogeneous Fenton catalyst obtained by the above preparation method in organic wastewater.

[0023] In the above technical solution, the organic wastewater contains phenol, wherein the concentration of phenol is 0.1-10 g / L, and the initial concentration of total organic carbon (TOC) is 74-7400 ppm, preferably 600 ppm to 800 ppm.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] This invention provides a method for preparing heterogeneous Fenton catalysts using iron-containing waste catalysts. This process has low cost and facilitates resource utilization. It not only makes full use of iron-containing waste catalysts and achieves a high element recovery rate, but also produces heterogeneous Fenton catalysts with high added value. These catalysts can effectively remove organic matter such as phenol from water bodies, and compared with existing heterogeneous Fenton catalysts, the mineralization of pollutants is more thorough. Detailed Implementation

[0026] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0027] In this invention, since phenol is a carbon-containing organic compound, the method for detecting phenol removal rate is the TOC (Total Organic Carbon) removal rate. In the following examples and comparative examples, the TOC of the solution was determined by a total organic carbon analyzer (TOC-L). CPH / CPN (Shimadzu) measurement.

[0028] TOC removal rate = (TOC reduction in solution / initial TOC) × 100%.

[0029]

Example 1

[0030] This embodiment illustrates the heterogeneous Fenton catalyst prepared using iron-containing waste catalyst and its preparation method according to the present invention.

[0031] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0032] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0033] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0034] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H6P2W9Mo9O. 62 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, which were then air-dried. The air-dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0035]

Example 2

[0036] This embodiment illustrates the heterogeneous Fenton catalyst prepared using iron-containing waste catalyst and its preparation method according to the present invention.

[0037] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0038] (2) The material obtained in step (1) was leached with 5 mol / L ammonium chloride solution at 110℃ for 3 h with a solid-liquid ratio of 1:15 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 98%, while Fe and Ce were not leached.

[0039] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0040] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H6P2W9Mo9O. 62 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, which were then air-dried. The air-dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0041]

Example 3

[0042] This embodiment illustrates the heterogeneous Fenton catalyst prepared using iron-containing waste catalyst and its preparation method according to the present invention.

[0043] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0044] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0045] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0046] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 100g of H6P2W9Mo9O. 6237.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, then air-dried. The dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0047]

Example 4

[0048] This embodiment illustrates the heterogeneous Fenton catalyst prepared using iron-containing waste catalyst and its preparation method according to the present invention.

[0049] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 12% by weight, Ce is 5.01% by weight, Fe is 50.02% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0050] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0051] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 25:1, which is not within the range of 8:1 to 20:1. The material obtained in step (2) was leached with 1 mol / L sulfuric acid solution at 60℃ for 2 h with a solid-liquid ratio of 1:4 g / mL. The content of Fe and Ce in the leaching residue was measured by inductively coupled plasma atomic emission spectrometry (ICP, Varian, 725-ES). The molar ratio of Fe to Ce was 19:1, which is within the range of 8:1 to 20:1.

[0052] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (3), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H6P2W9Mo9O. 62 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, then air-dried. The dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0053]

Example 5

[0054] This embodiment illustrates the heterogeneous Fenton catalyst prepared using iron-containing waste catalyst and its preparation method according to the present invention.

[0055] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 12% by weight, Ce is 5.01% by weight, Fe is 50.02% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0056] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0057] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 25:1, which is not within the range of 8:1 to 20:1. The material obtained in step (2) was leached with 9 mol / L hydrochloric acid solution at 140℃ for 24 h with a solid-liquid ratio of 1:25 g / mL. The content of Fe and Ce in the leaching residue was measured by inductively coupled plasma atomic emission spectrometry (ICP, Varian, 725-ES). The molar ratio of Fe to Ce was 10.5:1, which is within the range of 8:1 to 20:1.

[0058] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (3), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H6P2W9Mo9O. 62 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, which were then air-dried. The air-dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0059]

Example 6

[0060] This example illustrates the heterogeneous Fenton catalyst prepared using iron-containing waste catalyst and its preparation method according to the present invention.

[0061] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0062] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0063] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0064] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 400g of H6P2W9Mo9O. 62 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, which were then air-dried. The air-dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0065] Comparative Example 1

[0066] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0067] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0068] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0069] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), add 900g of β-molecular sieve, 1400g of attapulgite, 37.5g of cellulose, 97.5g of guar gum powder, and 300mL of 1.5% nitric acid solution, knead and extrude into strips, and air dry naturally. The dried solid is then dried at 100℃ for 24h, and then calcined at 600℃ for 6h in air atmosphere to obtain the heterogeneous Fenton catalyst product.

[0070] Comparative Example 2

[0071] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0072] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0073] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0074] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H6P2W. 18 O 62 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, which were then air-dried. The air-dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0075] Comparative Example 3

[0076] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0077] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0078] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0079] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H4SiW. 12 O 40 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, which were then air-dried. The air-dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0080] Comparative Example 4

[0081] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0082] (2) The material obtained in step (1) was leached with 1 mol / L ammonium carbonate solution at 60℃ for 2 h, with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 89%, while Fe and Ce were not leached.

[0083] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0084] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H3PMo. 12 O 40 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, which were then air-dried. The air-dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0085] Comparative Example 5

[0086] (1) 900g β-molecular sieve, 1400g attapulgite, 37.5g cellulose, 97.5g guar gum powder and 900g solution (containing 89.3g ferrous sulfate heptahydrate + 114g cerium nitrate hexahydrate, with a molar ratio of Fe to Ce of 11.4:1) knead and extrude into strips, and air dry naturally;

[0087] (2) The solid obtained in step (1) was dried at 100°C for 24 hours and then calcined at 600°C for 6 hours in air atmosphere to obtain a heterogeneous Fenton catalyst product.

[0088] Comparative Example 6

[0089] The method described in Example 1 differs from the method described in step (2) under the same leaching conditions, in which water is used as the leaching agent. The specific process is as follows:

[0090] (1) Iron-containing waste catalyst raw material (dry basis after removing organic matter, K is 7.71% by weight, Ce is 9.04% by weight, Fe is 40.96% by weight) was put into an industrial electric furnace and treated at 700℃ for 8 hours to obtain the material with a residual organic matter content of 0.2% by weight.

[0091] (2) The material obtained in step (1) was leached with water at 60℃ for 2 hours with a solid-liquid ratio of 1:10 g / mL. The concentrations of K, Fe, and Ce in the filtrate were measured using an inductively coupled plasma atomic emission spectrometer (ICP, Varian, 725-ES). The leaching rate was defined as the metal content in the filtrate divided by the total mass of metals in the raw material. Based on the ICP results, the leaching rate of K reached 30%, while Fe and Ce were not leached.

[0092] (3) The molar ratio of Fe to Ce in the leaching residue of step (2) is 11.4:1, which is in the range of 8:1 to 20:1;

[0093] (4) Take 162g of the solid residue obtained after solid-liquid separation in step (2), and add 900g of β-molecular sieve, 1350g of attapulgite, and 50g of H6P2W9Mo9O. 62 37.5g cellulose, 97.5g guar gum powder, and 300mL of 1.5% nitric acid solution were kneaded and extruded into strips, then air-dried. The dried solid was then dried at 100℃ for 24h, followed by calcination at 600℃ in air for 6h to obtain the heterogeneous Fenton catalyst product.

[0094]

Test Example 1

[0095] The performance of the Fenton catalyst was evaluated using a fixed-bed reactor. The experimental conditions were as follows: the simulated organic wastewater was a phenol-containing solution with a phenol concentration of approximately 1 g / L and an initial TOC concentration of 742.6 ppm. 300 mL of catalyst was loaded into the fixed-bed reactor. Phenol wastewater was first introduced until adsorption saturation, followed by the introduction of hydrogen peroxide. A steady-state was reached when the TOC no longer decreased. The TOC at this point was recorded, and the TOC removal rate was calculated. The evaluation results are listed in Table 1.

[0096] Table 1

[0097]

[0098]

[0099]

Test Example 2

[0100] The costs of Example 1 and Comparative Example 5 are calculated and listed in Table 2.

[0101] Among them, the outsourcing cost for treating iron-containing waste catalysts is about 6,000 yuan / ton, ferrous sulfate heptahydrate is 10,000 yuan / ton, β-molecular sieve is 20,000 yuan / ton, cerium nitrate hexahydrate is 10,000 yuan / ton, and attapulgite is 1,600 yuan / ton. In addition, since the amount of polyoxometalates, cellulose, and guar gum powder is small, their cost is negligible.

[0102] Table 2

[0103] serial number Cost (RMB / ton) Example 1 8500 Comparative Example 5 ＞11000

[0104] The above description is merely a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, based on the technical teachings provided by the present invention and as common knowledge in the field, other equivalent modifications and improvements can be made, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a heterogeneous Fenton catalyst, comprising the following steps: (1) The iron-containing waste catalyst after high-temperature roasting is subjected to ammonium leaching treatment to obtain leachate and leaching residue; (2) Optionally, the leaching residue obtained in step (1) is treated with Fe leaching agent to obtain a catalyst precursor; (3) The leaching residue obtained in step (1) or the catalyst precursor obtained in step (2) is mixed with additives and polyoxometalates, shaped, dried and calcined to obtain the heterogeneous Fenton catalyst. Step (1), the iron-containing waste catalyst is derived from waste styrene catalyst, wherein the iron-containing waste catalyst includes Fe, Ce and K; Step (3), the polyoxometalate is H6P2W9Mo9O 62 .

2. The preparation method according to claim 1, characterized in that, Step (1) The iron-containing waste catalyst also contains at least one of Mg, Cr, Mo, Ca, Zn and Cu.

3. The preparation method according to claim 1, characterized in that, Step (1), the composition of the iron-containing waste catalyst, based on the mass of the catalyst, includes 40%~60% Fe, 5%~12% K, 4%~12% Ce, and the total amount of other elements is less than 5%; the molar ratio of Fe to Ce in the iron-containing waste catalyst is 8:1~37:

1.

4. The preparation method according to claim 1, characterized in that, Step (1), the leaching agent used in the ammonium leaching treatment is NH4-containing + The solution; the concentration of the leaching agent is 0.5 mol / L ~ 10 mol / L, the reaction temperature is 20 ℃ ~ 150 ℃, the reaction time is 0.5 h ~ 48 h, and the solid-liquid ratio is 1:3 g / mL ~ 1:30 g / mL.

5. The preparation method according to claim 4, characterized in that, Step (1), the NH4-containing + The solution is selected from one or more of ammonia, ammonium chloride, ammonium nitrate, and ammonium carbonate.

6. The preparation method according to claim 1, characterized in that, Step (2) uses Fe leaching agents including one or more of hydrochloric acid, sulfuric acid, nitric acid, and perchloric acid; the concentration of hydrogen ions is 0.5 mol / L to 10 mol / L, the reaction temperature is 50 ℃ to 150 ℃, the reaction time is 0.5 h to 48 h, and the solid-liquid ratio is 1:3 g / mL to 1:30 g / mL.

7. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of Fe to Ce in the leaching residue obtained in step (1) or the catalyst precursor obtained in step (2) is 8:1 to 20:

1.

8. The preparation method according to claim 1, characterized in that, Step (3), the H6P2W9Mo9O 62 The added mass accounts for 1% to 10% of the total solid mass.

9. The heterogeneous Fenton catalyst obtained by the preparation method according to any one of claims 1-8.

10. The application of the heterogeneous Fenton catalyst according to claim 9 in organic wastewater.

11. The application according to claim 10, characterized in that, The organic wastewater contains phenol, with a concentration of 0.1-10 g / L and an initial total organic carbon (TOC) concentration of 74-7400 ppm.

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