Methanol reaction wastewater treatment method and device

Abstract

The present invention relates to the technical field of chemical wastewater treatment, and is a method and device for treating methanol reaction wastewater. The former is carried out according to the following method: First step, the wastewater generated after methanol reaction is subjected to sedimentation to remove particulate wastes, oil removal to remove organic matters in the upper layer of the wastewater, and filtration to remove particulate matters, suspended matters and organic macromolecular compounds suspended in the wastewater; Second step, a pretreatment agent is added to the wastewater treated in the first step for pretreatment to remove part of the organic matters in the wastewater; Third step, the wastewater treated in the second step is subjected to preheating treatment to make it reach the gasification state; Fourth step, the wastewater preheated and gasified in the third step undergoes a catalytic reaction with nitrogen or hydrogen under the action of a catalyst. The present invention can significantly improve the pH and COD indexes of the wastewater and meet the standard requirements for the discharge of industrial wastewater. The method has the characteristics of mild reaction conditions, short and simple process flow, and small equipment investment.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical wastewater treatment, and is a method and device for treating methanol reaction wastewater. Background Art

[0002] Methanol is an important basic chemical raw material with a relatively low price. Compared with oil and gas resources, coal resources in China are relatively abundant. As an important product of coal resources, China has a high methanol production capacity. Accelerating the utilization and development of methanol has attracted people's attention. Among them, the relatively hot research on methanol reactions includes the methanol-to-propylene / olefin (MTP / MTO) reaction, the methanol-to-aromatics (MTA) reaction, the methanol-to-gasoline (MTG) reaction, the benzene / toluene methanol alkylation reaction, the methanol coupling with light hydrocarbons (C2 / C3 / C4 / C5 / C6 alkanes, aromatics extraction raffinate oil, reforming topped oil, hydrocracking light naphtha, and pentane oil, etc.) reaction, etc., to prepare chemical raw materials such as lower olefins (ethylene and propylene) and aromatics (BTX, B: benzene, T: toluene, X: xylene) that are closely related to people's lives. These technologies have also made major breakthroughs.

[0003] The Chinese invention patent with the publication number CN109251119B discloses a method for producing alkylbenzene using a rotating packed bed reactor. In this method, benzene and an alkylating agent are subjected to an alkylation reaction in a rotating packed bed reactor equipped with an alkylation catalyst, and the product of the alkylation reaction is separated to obtain alkylbenzene. The selectivity and yield of the target product are relatively high, and the catalyst coking is effectively inhibited. The Chinese invention patent with the publication number CN112206811A discloses a methanol conversion to propylene catalyst, its preparation method and application. The preparation method of this methanol conversion to propylene catalyst includes mixing an aqueous solution of tetrapropylammonium bromide, an aqueous solution of sodium silicate, and an aqueous solution of sodium aluminate to obtain a mixed solution; crystallizing the mixed solution at 150°C to 210°C for at least 6 hours, and washing, drying, and calcining the crystallization product to obtain a Na-type ZSM-5 molecular sieve; performing ion exchange on the Na-type ZSM-5 molecular sieve with an ion exchange solution, and then washing, drying, and calcining to obtain an H-type ZSM-5 molecular sieve. This preparation method has a simple process flow and good repeatability, and is suitable for industrial production; the methanol conversion to propylene catalyst obtained by this preparation method has the characteristics of high propylene selectivity and good catalytic stability.

[0004] The above-mentioned technical method has the characteristics of high methanol conversion rate, high product yield and high product selectivity, providing a reliable technical route for the production of low-carbon olefins and aromatics, which are basic chemical raw materials for the national economy. However, since methanol involved in the reaction will generate water, and the amount of water generated is relatively large, accounting for 56.25% of methanol. During the research process, it was found that the pH of the generated water is less than 6.0, with strong acidity, basically maintained between 2.8 and 3.5. Especially before the reaction is cooled, the temperature of the wastewater is relatively high, seriously corroding equipment and pipelines, increasing the investment cost of the process technology; in addition, the COD in the wastewater is relatively high, basically greater than 5000 ppm, which cannot meet the requirements of industrial wastewater discharge standards, restricting the popularization and application of these technologies.

[0005] The Chinese invention patent with the publication number of CN110563539A discloses a treatment process and equipment for high-concentration wastewater in the production of styrene from methanol and toluene. The process includes the following steps: adding a flocculant to the high-concentration wastewater in the production of styrene from methanol and toluene for flocculation treatment to obtain flocculated wastewater; subjecting the flocculated wastewater to triple filtration to obtain filter residue and filtrate; subjecting the filtrate to primary distillation separation to obtain a high-concentration ethylbenzene solution and a high-concentration styrene solution; subjecting the high-concentration ethylbenzene solution to secondary distillation separation to obtain a methanol-toluene mixed solution and a high-purity ethylbenzene solution; subjecting the high-concentration styrene solution to refining separation to obtain high-purity styrene and catalyst powder. The treatment equipment includes a wastewater flocculation treatment unit, a triple filtration unit, a separation unit and a post-treatment unit connected in sequence. This process method is applicable to the technology of methanol to styrene, and does not mention the treatment of wastewater generated after the reaction of methanol to produce olefins, methanol coupling with light hydrocarbons and benzyl alcohol alkylation reaction.

[0006] The Chinese patent with the publication number of CN213803376U discloses a treatment system for wastewater from methanol aromatization process, including a stripping unit, a photocatalytic unit, an activated carbon adsorption unit, a distillation unit and a condensation unit, etc. The stripping unit is provided with a wastewater inlet, a wastewater outlet and an exhaust gas outlet. The exhaust gas outlet of the stripping unit is connected to the photocatalytic unit and the activated carbon adsorption unit through pipelines in sequence. The wastewater outlet of the stripping unit is connected to the distillation unit through pipelines. The gas-phase outlet of the distillation unit is connected to the condensation unit through pipelines. Its effect is that through the stripping of gas, volatile substances are separated from the wastewater in sequence, realizing the separation of volatile and non-volatile components, and then corresponding treatments are carried out on the liquid phase and the gas phase respectively. The liquid phase is separated by distillation to separate methanol and water to realize the recovery of methanol. For the aromatic hydrocarbon substances in the gas phase, they are removed by the method of advanced oxidation combined with physical adsorption, thereby realizing the purification and resource recovery of wastewater. Therefore, this patent mainly removes unreacted methanol and aromatic hydrocarbon substances, and does not involve the problem that the reaction wastewater shows acidity caused by the generation of organic acid substances from methanol reaction.

[0007] The Chinese invention patent with the publication number CN102050548B discloses a method for treating and recycling the wastewater from the methanol-to-olefins process. The method comprises the following steps: After the effluent from the MTO reactor recovers heat in the preheating boiler, it is cooled by a separation tower to separate high-concentration MTO wastewater. Then, the effluent from the MTO reactor is further cooled. An aqueous phase is obtained at the bottom of the separation tower, and olefin gas is obtained at the top of the separation tower. The olefin gas is further purified through compression and water washing operations. The aqueous phases from the bottom of the separation tower and the bottom of the water washing tower are subjected to stripping treatment. The aqueous phase at the bottom of the stripping tower is cooled by hot gas at the bottom of the tower, and then it is low-concentration MTO water. The low-concentration MTO water is subjected to homogenization adjustment, coagulation and precipitation treatment, aerobic aeration treatment, sedimentation treatment for the effluent from the aerobic aeration treatment, and flocculation treatment for the effluent from the sedimentation treatment. Finally, the COD of the treated wastewater can be reduced to 68 mg / L. However, the wastewater treatment process flow is long, the process is rather cumbersome, and the equipment is relatively complex, increasing the investment cost and the energy consumption of the device, which is not conducive to the popularization and application of the technology. Moreover, this process method is applicable to the technology of methanol to olefins, and does not mention the applications involving the reaction of methanol to form aromatics, the reaction of methanol coupling with light hydrocarbons, and the alkylation reaction of benzyl alcohol, nor does it mention the pH of the wastewater, and does not take into account the problems of low pH and high COD, so its application has certain limitations. Summary of the Invention

[0008] The present invention provides a method and device for treating methanol reaction wastewater, overcoming the deficiencies of the above-mentioned prior art, and effectively solving the problem that the existing treatment of methanol reaction wastewater fails to take into account both low pH and high COD.

[0009] One of the technical solutions of the present invention is achieved by the following measures: A method for treating methanol reaction wastewater is carried out according to the following method:

[0010] In the first step, the wastewater generated after methanol reaction is subjected to precipitation to remove particulate wastes, oil removal to remove the organic matters on the upper layer of the wastewater, and filtration to remove the particulate matters, suspended matters and organic macromolecular compounds suspended in the wastewater.

[0011] In the second step, a pretreatment agent is added to the wastewater treated in the first step for pretreatment to remove part of the organic matters in the wastewater.

[0012] In the third step, the wastewater treated in the second step is preheated to reach the gasification state.

[0013] In the fourth step, the wastewater preheated and gasified in the third step undergoes a catalytic reaction with nitrogen or hydrogen under the action of a catalyst.

[0014] In the fifth step, the wastewater after the reaction in the fourth step is subjected to rectification extraction. After cooling, the treated wastewater meets the discharge standard. Meanwhile, trace methanol and aromatic organic compounds remaining in the wastewater are recovered through rectification extraction.

[0015] The following is a further optimization or / and improvement of one of the above-mentioned inventive technical solutions:

[0016] In the above-mentioned first step, the filtration is carried out using a nanoscale ultrafiltration membrane.

[0017] In the above-mentioned first step, the precipitation time is 0.5 h to 3 h.

[0018] In the above-mentioned second step, the pretreatment agent is one of porous activated carbon, magnesium-modified ZSM-5 molecular sieve, and magnesium-modified β molecular sieve.

[0019] In the above-mentioned second step, the conditions for pretreatment are normal pressure, a temperature of 50°C to 150°C, and an airspeed of 0.2 h -1 to 5 h -1 .

[0020] In the above-mentioned fourth step, the catalyst is one or two of magnesium-alkali zeolite type, hydrotalcite MgO-Fe2O3, or hydrotalcite MgO-Fe2O3 / ZSM-5 bifunctional catalyst.

[0021] In the above-mentioned fourth step, the reaction temperature of the catalytic reaction is 300°C to 600°C, the reaction pressure is 0 to 3.0 MPa, and the total liquid hourly space velocity is 0.2 h -1 to 5 h -1 .

[0022] In the above-mentioned fifth step, the rectification is carried out in a packed rectification column. The bottom temperature of the column is 40°C to 100°C, the bottom operating pressure is 10 KPa to 50 KPa, the top temperature of the column is 40°C to 100°C, the top operating pressure is 5 KPa to 40 KPa, and the reflux ratio is 3 to 15.

[0023] The second technical solution of the present invention is achieved by the following measures: An apparatus for implementing a methanol reaction wastewater treatment method includes a sedimentation tank, a pre-processor, a pre-heater, a catalytic reactor, a distillation column, a cooler, an air cooler, and an oil remover. The inlet of the sedimentation tank is fixedly connected to a first wastewater pipeline. There is a fixed connection between the first discharge port above the sedimentation tank and the oil remover through an oil extraction pipeline. There is a fixed connection between the second discharge port of the sedimentation tank and the inlet of the pre-processor through a second wastewater pipeline. The third discharge port of the sedimentation tank is fixedly connected to a solid waste pipeline. There is a fixed connection between the outlet of the pre-processor and the inlet of the pre-heater through a third wastewater pipeline. There is a fixed connection between the outlet of the pre-heater and the catalytic reactor through a fourth wastewater pipeline. A gas addition pipeline is fixedly connected to the fourth wastewater pipeline. There is a fixed connection between the outlet of the catalytic reactor and the inlet of the distillation column through a fifth wastewater pipeline. There is a fixed connection between the first discharge port at the upper part of the distillation column and the air cooler through a recovery pipeline. There is a fixed connection between the second discharge port at the lower part of the distillation column and the cooler through a sixth wastewater pipeline.

[0024] The following is a further optimization and / or improvement of the second technical solution of the above invention:

[0025] A filter membrane is provided at the second discharge port in the above sedimentation tank, a packing layer is provided in the pre-processor, and a catalyst bed layer is provided in the catalytic reactor.

[0026] The present invention provides a method for improving the treatment effect of wastewater generated by methanol reaction, which is applicable to wastewater generated by methanol-to-olefins reaction, methanol aromatization reaction, benzyl alcohol alkylation reaction, methanol light hydrocarbon coupling reforming reaction, etc. It can simultaneously solve the problems that the pH and COD indexes of the wastewater after methanol reaction seriously do not meet the discharge standards, corrode equipment and pipelines, may cause dangerous accidents and pollute the environment. It can significantly improve the pH and COD indexes of the wastewater (pH > 6.0, COD < 60 mg / L) to meet the standard requirements for the discharge of industrial wastewater. This method has the characteristics of mild reaction conditions, short and simple process flow, and small equipment investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Attached Figure 1 is a schematic process flow diagram of the present invention.

[0028] The codes in the drawings are respectively: 1 is the sedimentation tank, 2 is the pre-processor, 3 is the pre-heater, 4 is the catalytic reactor, 5 is the distillation column, 6 is the cooler, 7 is the air cooler, 8 is the oil remover, 9 is the first wastewater pipeline, 10 is the oil extraction pipeline, 11 is the second wastewater pipeline, 12 is the solid waste pipeline, 13 is the third wastewater pipeline, 14 is the fourth wastewater pipeline, 15 is the gas addition pipeline, 16 is the fifth wastewater pipeline, 17 is the recovery pipeline, 18 is the sixth wastewater pipeline, 19 is the filter membrane, 20 is the packing layer, and 21 is the catalyst bed layer. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention is not limited by the following embodiments, and the specific implementation manners can be determined according to the technical solution of the present invention and the actual situation. Various chemical reagents and chemical supplies mentioned in the present invention are well-known and commonly used chemical reagents and chemical supplies in the prior art unless otherwise specified; the percentages in the present invention are mass percentages unless otherwise specified; normal temperature and room temperature in the present invention generally refer to the temperature from 15°C to 25°C, and are generally defined as 25°C.

[0030] In the present invention, unless otherwise specified, the equipment and devices used are the existing well-known and commonly used equipment and devices in the art.

[0031] The present invention will be further described below in conjunction with embodiments:

[0032] Embodiment 1: The method for treating methanol reaction wastewater is carried out according to the following steps:

[0033] First step, the wastewater generated after methanol reaction is subjected to precipitation to remove particulate waste, oil removal to remove the organic matter on the upper layer of the wastewater, and filtration to remove the particulate matter, suspended matter and organic macromolecular compounds suspended in the wastewater.

[0034] Second step, a pretreatment agent is added to the wastewater treated in the first step for pretreatment to remove part of the organic matter in the wastewater.

[0035] Third step, the wastewater treated in the second step is preheated to reach the gasification state.

[0036] Fourth step, the wastewater preheated and gasified in the third step undergoes a catalytic reaction with nitrogen or hydrogen under the action of a catalyst.

[0037] Fifth step, the wastewater after the fourth step reaction is subjected to rectification extraction. After the treated wastewater is cooled, it reaches the discharge standard, and at the same time, the trace methanol and aromatic organic compounds remaining in the wastewater are recovered by rectification extraction.

[0038] Embodiment 2: As an optimization of the above embodiment, in the first step, the filtration is carried out using a nanoscale ultrafiltration membrane.

[0039] Embodiment 3: As an optimization of the above embodiment, in the first step, the precipitation time is 0.5 h to 3 h. The precipitation time can be 1 h to 2.5 h.

[0040] Embodiment 4: As an optimization of the above embodiment, in the second step, the pretreatment agent is one of porous activated carbon, magnesium-modified ZSM-5 molecular sieve, and magnesium-modified β molecular sieve.

[0041] In the present invention, the carbon content of the porous activated carbon is 50% to 95%, the pore size is 2 μm to 50 μm, the specific surface area is greater than 300 m 2 / g, and the pore volume is greater than 0.30 m3 / g; The magnesium content of the magnesium-modified ZSM-5 molecular sieve is 0.5% to 5% (mass content), and the silica-alumina molar ratio SiO2 / Al2O3 of the ZSM-5 molecular sieve is 30 to 500. Preferably, the silica-alumina molar ratio SiO2 / Al2O3 of the ZSM-5 molecular sieve can be 100 to 300, the pore volume is greater than 0.40 m 3 / g, and the specific surface area is greater than 300 m 2 / g. The magnesium content of the magnesium-modified β molecular sieve is 0.5% to 5% (mass content), and the silica-alumina molar ratio SiO2 / Al2O3 of the β molecular sieve is 50 to 300. Preferably, the silica-alumina molar ratio SiO2 / Al2O3 of the β molecular sieve is 100 to 250, the pore volume is greater than 0.30 m 3 / g, and the specific surface area is greater than 200 m 2 / g. The magnesium-modified ZSM-5 molecular sieve and the magnesium-modified β molecular sieve can be prepared by the wet impregnation method. The specific steps can be: First, weigh 60% to 120% of the mass of the ZSM-5 and β molecular sieves of water and place it in a beaker, and place it in a water bath (20°C to 50°C); then weigh a certain amount of the modifier (compound of magnesium, selected from one or two of magnesium nitrate, magnesium sulfate, and magnesium chloride) according to the modification amount of the ZSM-5 and β molecular sieves, add it to the beaker and stir to dissolve the modifier; then weigh a certain amount of ZSM-5 or β molecular sieve and slowly add it to the modifier solution; then let it stand at 20°C to 65°C for 5 h to 48 h; after the standing time is up, transfer the modified ZSM-5 molecular sieve or β molecular sieve to an oven, dry it at 50°C to 140°C for 6 h to 18 h, and then place it in a muffle furnace and calcine it at 400°C to 650°C for 2 h to 10 h; thus obtaining the pretreating agent of the modified magnesium-modified ZSM-5 molecular sieve or magnesium-modified β molecular sieve.

[0042] Example 5: As an optimization of the above example, in the second step, the pretreatment conditions are normal pressure, the temperature is 50°C to 150°C, and the space velocity is 0.2 h -1 to 5 h -1 .

[0043] Example 6: As an optimization of the above example, in the fourth step, the catalyst is one or two of magnesium-zeolite catalysts, hydrotalcite MgO-Fe2O3, or hydrotalcite MgO-Fe2O3 / ZSM-5 bifunctional catalysts.

[0044] In the present invention, the silica-alumina molar ratio SiO2 / Al2O3 of the magnesium-zeolite catalyst is 10 to 200. Preferably, the silica-alumina molar ratio SiO2 / Al2O3 of the magnesium-zeolite catalyst is 50 to 150; for the hydrotalcite MgO-Fe2O3 / ZSM-5 bifunctional catalyst, the silica-alumina molar ratio SiO2 / Al2O3 of the ZSM-5 molecular sieve is 100 to 300.

[0045] Example 7: As an optimization of the above example, in the fourth step, the reaction temperature of the catalytic reaction is 300°C to 600°C, the reaction pressure is 0 to 3.0 MPa, and the total liquid hourly space velocity is 0.2 h -1 to 5 h -1 .

[0046] Example 8: As an optimization of the above example, in the fifth step, the rectification is carried out in a packed rectification column 5. The bottom temperature of the column is 40°C to 100°C, the bottom operating pressure is 10 KPa to 50 KPa, the top temperature of the column is 40°C to 100°C, the top operating pressure is 5 KPa to 40 KPa, and the reflux ratio is 3 to 15.

[0047] Example 9: As shown Figure 1 , the device for treating methanol reaction wastewater of this embodiment includes a sedimentation tank 1, a pre-processor 2, a pre-heater 3, a catalytic reactor 4, a rectification column 5, a cooler 6, an air cooler 7, and an oil remover 8. The feed inlet of the sedimentation tank 1 is fixedly connected to a first wastewater pipeline 9. There is a fixed connection between the first discharge port above the sedimentation tank 1 and the oil remover 8 with an oil extraction pipeline 10. There is a fixed connection between the second discharge port of the sedimentation tank 1 and the feed inlet of the pre-processor 2 with a second wastewater pipeline 11. The third discharge port of the sedimentation tank 1 is fixedly connected to a solid waste pipeline 12. There is a fixed connection between the discharge port of the pre-processor 2 and the feed inlet of the pre-heater 3 with a third wastewater pipeline 13. There is a fixed connection between the discharge port of the pre-heater 3 and the catalytic reactor 4 with a fourth wastewater pipeline 14. A gas addition pipeline 15 is fixedly connected to the fourth wastewater pipeline 14. There is a fixed connection between the discharge port of the catalytic reactor 4 and the feed inlet of the rectification column 5 with a fifth wastewater pipeline 16. There is a fixed connection between the first discharge port at the upper part of the rectification column 5 and the air cooler 7 with a recovery pipeline 17. There is a fixed connection between the second discharge port at the lower part of the rectification column 5 and the cooler 6 with a sixth wastewater pipeline 18.

[0048] Example 10: As shown Figure 1 , as an optimization of the above Example 9, a filter membrane 19 is provided at the second discharge port in the sedimentation tank 1, a packing layer 20 is provided in the pre-processor 2, and a catalyst bed layer 21 is provided in the catalytic reactor 4.

[0049] In the present invention, the catalytic reactor 4 is not limited to the types of fixed bed, fluidized bed or moving bed reactors. During use, the wastewater generated after the methanol reaction enters the filtration sedimentation tank 1 for sedimentation. An oil removal machine 8 is installed at the upper part of the sedimentation tank 1. After standing for a certain period of time, the organic substances in the wastewater accumulate to a certain amount and float on the upper part. The organic substances floating on the water surface are removed by the oil removal machine 8. At the same time, the impurity particulate waste residues that may remain in the water during the previous reaction stage settle at the bottom of the sedimentation tank 1. After accumulating to a certain amount, they are discharged through the solid waste pipeline 12. A filter membrane 19 (a nano-level ultrafiltration membrane) is provided at the second discharge port of the sedimentation tank 1. The preliminarily purified wastewater enters the pre-processor 2 through the outlet and is pre-treated under the action of a pre-treatment agent to remove part of the organic substances in the wastewater. After the wastewater enters the pre-heater 3, it undergoes pre-heating treatment to reach the gasification state. The gasified wastewater enters the catalytic reactor 4 together with nitrogen or hydrogen and undergoes a catalytic reaction in the catalyst bed 21. The reacted wastewater enters the rectification column 5 for rectification extraction. The gas at the upper outlet of the rectification column 5 enters the air cooler 7 to further cool and recover the trace methanol and aromatic organic compounds remaining in the wastewater. The wastewater after passing through the rectification column 5 enters the cooler 6 and can meet the COD and pH requirements of the external drainage of chemical production devices after cooling. Among them, the temperature of the air cooler 7 can be 0 to 30 °C, and the temperature of the cooler 6 can be 0 to 30 °C.

[0050] Example 11:

[0051] The COD of the wastewater generated by the methanol reaction is 5050 mg / L, and the pH is 3.10. It is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it stands in the sedimentation tank 1 for 1 h; the pre-treatment agent used in the pre-processor 2 is porous activated carbon, and the process conditions are a temperature of 60 °C and a space velocity of 0.5 h -1 , at atmospheric pressure; the catalyst loaded in the catalytic reactor 4 is mordenite (the molar ratio of silicon to aluminum SiO2 / Al2O3 = 60), and the process conditions are a temperature of 450 °C, a pressure of 0.5 MPa, and a space velocity of 0.5 h -1 ; the bottom temperature of the rectification column 5 is 80 °C, the pressure is 20 KPa, the top temperature is 60 °C, and the pressure is 10 KPa; the temperature of the air cooler 7 is 5 °C, and the temperature of the cooler 6 is 10 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 57 mg / L, and the pH is 6.50.

[0052] Example 12:

[0053] The COD of the wastewater generated by the methanol reaction is 7872 mg / L, and the pH is 3.45. It is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it stands in the sedimentation tank 1 for 1.5 h; the pre-treatment agent used in the pre-processor 2 is porous activated carbon, and the process conditions are a temperature of 100 °C and a space velocity of 0.7 h -1, at atmospheric pressure; the catalyst filled in the catalytic reactor 4 is magnesium alkali zeolite (the molar ratio of silicon to aluminum SiO2 / Al2O3 = 100), and the process conditions are a temperature of 400 °C, a pressure of 0.3 MPa, and a space velocity of 0.8 h -1 ; the bottom temperature of the distillation column 5 is 90 °C, the pressure is 15 KPa, the top temperature is 70 °C, and the pressure is 10 KPa; the temperature of the air cooler 7 is 0 °C, and the temperature of the cooler 6 is 10 °C. After cooling, the sample is collected for testing and analysis. The COD in the treated water is 58 mg / L, and the pH is 6.55.

[0054] Example 13:

[0055] The wastewater produced by the methanol reaction has a COD of 6803 mg / L and a pH of 4.52, and is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is left standing in the sedimentation tank 1 for 2.0 h; the pretreatment agent used in the preprocessor 2 is magnesium-modified ZSM-5 molecular sieve (the mass content of magnesium is 1.5%, and the molar ratio of silicon to aluminum SiO2 / Al2O3 = 150), and the process conditions are a temperature of 90 °C and a space velocity of 1.0 h -1 , at atmospheric pressure; the catalyst filled in the catalytic reactor 4 is hydrotalcite MgO-Fe2O3, and the process conditions are a temperature of 380 °C, a pressure of 1.0 MPa, and a space velocity of 1.5 h -1 ; the bottom temperature of the distillation column 5 is 70 °C, the pressure is 25 KPa, the top temperature is 50 °C, the pressure is 15 KPa, 0.5 MPa, 1.0 h -1 ; the temperature of the air cooler 7 is 0 °C, and the temperature of the cooler 6 is 5 °C. After cooling, the sample is collected for testing and analysis. The COD in the treated water is 55 mg / L, and the pH is 6.60.

[0056] Example 14:

[0057] The wastewater produced by the methanol reaction has a COD of 6511 mg / L and a pH of 3.02, and is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is left standing in the sedimentation tank 1 for 1.0 h; the pretreatment agent used in the preprocessor 2 is magnesium-modified β molecular sieve (the mass content of magnesium is 2.0%, and the molar ratio of silicon to aluminum SiO2 / Al2O3 = 120), and the process conditions are a temperature of 100 °C and a space velocity of 1.5 h -1 , at atmospheric pressure; the catalyst filled in the catalytic reactor 4 is a hydrotalcite MgO-Fe2O3 / ZSM-5 bifunctional catalyst (the molar ratio of silicon to aluminum SiO2 / Al2O3 = 120), and the process conditions are a temperature of 360 °C, a pressure of 0.3 MPa, and a space velocity of 1.5 h -1; The bottom temperature of the distillation column 5 is 65 °C, the pressure is 30 KPa, the top temperature is 55 °C, and the pressure is 20 KPa; the temperature of the air cooler 7 is 5 °C, and the temperature of the cooler 6 is 5 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 52 mg / L, and the pH is 6.80.

[0058] Example 15:

[0059] The wastewater produced by the methanol reaction has a COD of 7180 mg / L and a pH of 2.98, and is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is left standing in the sedimentation tank 1 for 2.5 h. The pretreatment agent used in the pre-processor 2 is magnesium-modified ZSM-5 molecular sieve (the mass content of magnesium is 2.5%, and the silica-alumina molar ratio SiO2 / Al2O3 = 150), and the process conditions are 90 °C and 1.0 h -1 , at atmospheric pressure; the catalyst loaded in the catalytic reactor 4 is a hydrotalcite MgO-Fe2O3 / ZSM-5 bifunctional catalyst (the silica-alumina molar ratio SiO2 / Al2O3 = 90), and the process conditions are 400 °C, 0.5 MPa, and 1.0 h -1 , the bottom temperature of the distillation column 5 is 85 °C, the pressure is 20 KPa, the top temperature is 70 °C, the pressure is 10 KPa, the temperature of the air cooler 7 is 10 °C, and the temperature of the cooler 6 is 5 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 50 mg / L, and the pH is 6.60.

[0060] Example 16:

[0061] The wastewater produced by the methanol reaction has a COD of 9318 mg / L and a pH of 3.40, and is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is left standing in the sedimentation tank 1 for 0.5 h; the pretreatment agent used in the pre-processor 2 is magnesium-modified ZSM-5 molecular sieve (the mass content of magnesium is 1.5%, and the silica-alumina molar ratio SiO2 / Al2O3 = 180), and the process conditions are a temperature of 100 °C and a space velocity of 1.5 h -1 , at atmospheric pressure; the catalyst loaded in the catalytic reactor 4 is ferrierite (the silica-alumina molar ratio SiO2 / Al2O3 = 80), and the process conditions are a temperature of 460 °C, a pressure of 1.0 MPa, and a space velocity of 1.2 h -1 ; the bottom temperature of the distillation column 5 is 50 °C, the pressure is 40 KPa, the top temperature is 40 °C, the pressure is 30 KPa; the temperature of the air cooler 7 is 10 °C, and the temperature of the cooler 6 is 0 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 46 mg / L, and the pH is 6.70.

[0062] Example 17:

[0063] The wastewater produced by the methanol reaction has a COD of 8560 mg / L and a pH of 3.50, and is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is left standing in sedimentation tank 1 for 2.0 h; the pretreatment agent used in preprocessor 2 is porous activated carbon, and the process conditions are a temperature of 70 °C and an airspeed of 0.8 h -1 , at atmospheric pressure; the catalyst filled in catalytic reactor 4 is hydrotalcite MgO-Fe2O3, and the process conditions are a temperature of 480 °C, a pressure of 0.8 MPa, and an airspeed of 1.5 h -1 ; the bottom temperature of distillation column 5 is 65 °C, the pressure is 35 KPa, the top temperature is 50 °C, and the pressure is 20 KPa; the temperature of air cooler 7 is 10 °C, and the temperature of cooler 6 is 15 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 55 mg / L, and the pH is 6.20.

[0064] Example 18:

[0065] The wastewater produced by the methanol reaction has a COD of 10165 mg / L and a pH of 3.70, and is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is left standing in sedimentation tank 1 for 3.0 h; the pretreatment agent used in preprocessor 2 is magnesium-modified porous activated carbon, and the process conditions are a temperature of 90 °C and an airspeed of 1.0 h -1 , at atmospheric pressure; the catalyst filled in catalytic reactor 4 is a hydrotalcite MgO-Fe2O3 / ZSM-5 bifunctional catalyst (silica-alumina molar ratio SiO2 / Al2O3 = 270), and the process conditions are a temperature of 520 °C, a pressure of 1.5 MPa, and an airspeed of 1.2 h -1 ; the bottom temperature of distillation column 5 is 50 °C, the pressure is 20 KPa, the top temperature is 40 °C, and the pressure is 10 KPa. The temperature of air cooler 7 is 15 °C, and the temperature of cooler 6 is 10 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 57 mg / L, and the pH is 6.70.

[0066] Example 19:

[0067] The wastewater produced by the methanol reaction has a COD of 9985 mg / L and a pH of 3.25, and is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is left standing in sedimentation tank 1 for 2.5 h; the pretreatment agent used in preprocessor 2 is magnesium-modified β-zeolite (the mass content of magnesium is 2.5%, and the silica-alumina molar ratio SiO2 / Al2O3 = 300), and the process conditions are a temperature of 100 °C and an airspeed of 2.5 h -1 , at atmospheric pressure; the catalyst filled in catalytic reactor 4 is hydrotalcite MgO-Fe2O3 / ZSM-5 (silica-alumina molar ratio SiO2 / Al2O3 = 180), and the process conditions are a temperature of 560 °C, a pressure of 2.0 MPa, and an airspeed of 2.0 h -1; The bottom temperature of the rectification column 5 is 95 °C, the pressure is 20 KPa, the top temperature is 85 °C, and the pressure is 10 KPa; the temperature of the air cooler 7 is 5 °C, and the temperature of the cooler 6 is 8 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 59 mg / L, and the pH is 6.90.

[0068] Example 20:

[0069] The COD of the wastewater generated by the methanol reaction is 8612 mg / L, and the pH is 4.12, and it is treated according to the methanol reaction wastewater treatment method of the present invention. Among them, it is statically settled in the sedimentation tank 1 for 1 h; the pretreatment agent used in the preprocessor 2 is a magnesium-modified ZSM-5 molecular sieve (the mass content of magnesium is 3.5%, and the silica-alumina molar ratio SiO2 / Al2O3 = 270), and the process conditions are a temperature of 120 °C and a space velocity of 3.0 h -1 , at atmospheric pressure; the catalyst loaded in the catalytic reactor 4 is hydrotalcite MgO-Fe2O3 / ZSM-5 (the silica-alumina molar ratio SiO2 / Al2O3 = 150), and the process conditions are a temperature of 520 °C, a pressure of 2.5 MPa, and a space velocity of 3.0 h -1 ; The bottom temperature of the rectification column 5 is 70 °C, the pressure is 15 KPa, the top temperature is 60 °C, and the pressure is 5 KPa; the temperature of the air cooler 7 is 0 °C, and the temperature of the cooler 6 is 0 °C. After cooling, the sample is collected for test analysis. The COD in the treated water is 55 mg / L, and the pH is 6.50.

[0070] In summary, the present invention provides a method for improving the treatment effect of wastewater generated by methanol reaction, which is applicable to wastewater generated by methanol-to-olefins reaction, methanol aromatization reaction, benzyl alcohol alkylation reaction, methanol light hydrocarbon coupling reforming reaction, etc.; it can simultaneously solve the problems that the pH and COD indexes of the wastewater after methanol reaction seriously do not meet the discharge standards, corrode equipment and pipelines, and may cause dangerous accidents and environmental pollution; it can significantly improve the pH and COD indexes of the wastewater (pH > 6.0, COD < 60 mg / L) to meet the standard requirements for industrial wastewater discharge. This method has the characteristics of mild reaction conditions, short and simple process flow, and small equipment investment.

[0071] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effects. Non-essential technical features can be increased or decreased according to actual needs to meet the requirements of different situations.

Claims

1. A method for treating methanol reaction wastewater, characterized in that It is carried out as follows: In the first step, the wastewater generated after the methanol reaction is subjected to precipitation to remove particulate wastes, oil removal to remove the organic matter on the upper layer of the wastewater, and filtration to remove the particulate matters, suspended matters and organic macromolecular compounds suspended in the wastewater; In the second step, a pretreatment agent is added to the wastewater treated in the first step for pretreatment to remove part of the organic matter in the wastewater; In the third step, the wastewater treated in the second step is preheated to reach the gasification state; In the fourth step, the wastewater preheated and gasified in the third step undergoes a catalytic reaction with nitrogen or hydrogen under the action of a catalyst; In the fifth step, the wastewater after the fourth step reaction is subjected to rectification extraction. After the treated wastewater is cooled, it reaches the discharge standard. At the same time, the rectification extraction recovers the trace methanol and aromatic organic compounds remaining in the wastewater; The wastewater generated after the methanol reaction includes the wastewater generated by the methanol-to-olefins reaction, methanol aromatization reaction, benzyl alcohol alkylation reaction and methanol light hydrocarbon coupling and upgrading reaction; the pH of the treated wastewater is greater than 6.0, and the COD is less than 60 mg / L.

2. The methanol reaction wastewater treatment method according to claim 1, characterized in that In the first step, the filtration is carried out by using a nanoscale ultrafiltration membrane; or / and, in the first step, the precipitation time is 0.5 h to 3 h.

3. The methanol reaction wastewater treatment method according to claim 1 or 2, characterized in that In the second step, the pretreatment agent is one of porous activated carbon, magnesium-modified ZSM-5 molecular sieve, and magnesium-modified β molecular sieve.

4. The methanol reaction wastewater treatment method according to claim 1 or 2, characterized in that In the second step, the conditions for pretreatment are normal pressure, a temperature of 50°C to 150°C, and a space velocity of 0.2 h -1 to 5 h -1 ; and / or, in the fourth step, the catalyst is one or two of the mordenite zeolite type, hydrotalcite MgO-Fe2O3, or the bifunctional catalyst hydrotalcite MgO-Fe2O3 / ZSM-5.

5. The method for treating methanol reaction wastewater according to claim 3, characterized in that In the second step, the conditions for pretreatment are normal pressure, a temperature of 50°C to 150°C, and a space velocity of 0.2 h -1 to 5 h -1 ; or / and, in the fourth step, the catalyst is one or two of the magnesium-alkali zeolite type, hydrotalcite MgO-Fe2O3, or the bifunctional catalyst hydrotalcite MgO-Fe2O3 / ZSM-5.

6. The methanol reaction wastewater treatment method according to claim 1 or 2 or 5, characterized in that In the fourth step, the reaction temperature for the catalytic reaction is 300°C to 600°C, the reaction pressure is 0 to 3.0 MPa, and the total liquid hourly space velocity is 0.2 h -1 to 5 h -1 ; or / and, in the fifth step, the rectification is carried out in a packed rectification column, the bottom temperature of the column is 40°C to 100°C, the bottom operating pressure is 10 KPa to 50 KPa, the top temperature of the column is 40°C to 100°C, the top operating pressure is 5 KPa to 40 KPa, and the reflux ratio is 3 to 15.

7. The methanol reaction wastewater treatment method according to claim 3, characterized in that In the fourth step, the reaction temperature for the catalytic reaction is 300°C to 600°C, the reaction pressure is 0 to 3.0 MPa, and the total liquid hourly space velocity is 0.2 h -1 to 5 h -1 ; or / and, in the fifth step, the rectification is carried out in a packed rectification column, the bottom temperature of the column is 40°C to 100°C, the bottom operating pressure is 10 KPa to 50 KPa, the top temperature of the column is 40°C to 100°C, the top operating pressure is 5 KPa to 40 KPa, and the reflux ratio is 3 to 15.

8. The methanol reaction wastewater treatment method according to claim 4, characterized in that In the fourth step, the reaction temperature for the catalytic reaction is 300°C to 600°C, the reaction pressure is 0 to 3.0 MPa, and the total liquid hourly space velocity is 0.2 h -1 to 5 h -1 ; or / and, in the fifth step, the rectification is carried out in a packed rectification column, the bottom temperature of the column is 40°C to 100°C, the bottom operating pressure is 10 KPa to 50 KPa, the top temperature of the column is 40°C to 100°C, the top operating pressure is 5 KPa to 40 KPa, and the reflux ratio is 3 to 15.

9. An apparatus for implementing the methanol reaction wastewater treatment method according to any one of claims 1 to 8, characterized in that It includes a sedimentation tank, a preprocessor, a preheater, a catalytic reactor, a rectification tower, a cooler, an air cooler, and an oil remover. The inlet of the sedimentation tank is fixedly connected to a first wastewater pipeline. There is a fixed connection between the first discharge port above the sedimentation tank and the oil remover with an oil extraction pipeline. There is a fixed connection between the second discharge port of the sedimentation tank and the inlet of the preprocessor with a second wastewater pipeline. The third discharge port of the sedimentation tank is fixedly connected to a solid waste pipeline. There is a fixed connection between the outlet of the preprocessor and the inlet of the preheater with a third wastewater pipeline. There is a fixed connection between the outlet of the preheater and the catalytic reactor with a fourth wastewater pipeline. A gas addition pipeline is fixedly connected to the fourth wastewater pipeline. There is a fixed connection between the outlet of the catalytic reactor and the inlet of the rectification tower with a fifth wastewater pipeline. There is a fixed connection between the first discharge port at the upper part of the rectification tower and the air cooler with a recovery pipeline. There is a fixed connection between the second discharge port at the lower part of the rectification tower and the cooler with a sixth wastewater pipeline.

10. The device for implementing the methanol reaction wastewater treatment method according to claim 9, characterized in that A filter membrane is arranged at the second discharge port in the sedimentation tank, a packing layer is arranged in the preprocessor, and a catalyst bed layer is arranged in the catalytic reactor.

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