Efficient desulfurization method for preparing methanol from coke oven gas

Abstract

The invention discloses an efficient desulfurization method for preparing methanol from coke oven gas, and belongs to the technical field of coke oven gas resource recovery. The invention is used for solving the technical problem that the selectivity and efficiency of sulfide removal and the purity of methanol need to be further improved in the process of preparing methanol from coke oven gas in the prior art, and relates to an efficient desulfurization method for preparing methanol from coke oven gas, which comprises the following steps: desulfurizing the coke oven gas by using modified Cu-BTC; performing component separation on the desulfurized coke oven gas; the method comprises the following steps: absorbing methane and other small molecular hydrocarbons by using Cu-ZSM-5, and reforming steam to obtain hydrogen and carbon monoxide; methanol is prepared using gas separated from coke oven gas and gas obtained by steam reforming. According to the experiment, Cu-BTC and ZSM-5 are modified, so that the selectivity and efficiency of recovery of small molecular hydrocarbons such as hydrogen sulfide and methane are improved, and the step of steam reforming of small molecular hydrocarbons such as methane is adjusted, so that the concentration of methanol is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of coke oven gas resource recovery, and in particular to a high-efficiency desulfurization method for preparing methanol from coke oven gas. Background Art

[0002] Coke oven gas is a by-product of the coking process and has a high energy content. Therefore, it is widely used in power generation, preparation of natural gas, hydrogen and methanol. Among them, methanol is the raw material for the production of many chemicals and is generally produced using natural gas and coke oven gas. However, the domestic environment of more coal and less gas has greatly restricted the production of methanol from natural gas. Therefore, the method of producing methanol from coke oven gas needs to be continuously improved and developed to cope with the growing demand for methanol.

[0003] The preparation of methanol usually requires the use of catalysts, such as copper-based or iron-based catalysts. Sulfides in high-sulfur coal gas will react with catalysts to form sulfides, which will poison the catalyst surface, reduce its catalytic activity and life, and lead to a decrease in the efficiency of methanol synthesis reaction; if sulfides are not effectively removed during the methanol preparation process, it may lead to the emission of sulfides such as hydrogen sulfide, which will have a negative impact on the environment and violate environmental protection regulations.

[0004] In the prior art, sulfide recovery in coke oven gas mostly adopts alkaline washing method and catalytic oxidation method. The former has too high requirements on the recovery device and has low selectivity, while the latter requires higher temperature and catalyst coordination, and the selectivity also needs to be improved. In the process of preparing methanol in the prior art, the components of coke oven gas are not separated sufficiently, and the reforming of small molecular hydrocarbons such as methane is carried out in the methanol tower, which leads to an increase in side reactions in the methanol tower and a change in the proportion of raw gas, so that the purity of methanol needs to be further improved.

[0005] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0006] The present invention aims to provide a highly efficient desulfurization method for preparing methanol from coke oven gas, which is used to solve the technical problems that the selectivity and efficiency of sulfide removal and the purity of methanol in the process of preparing methanol from coke oven gas in the existing process need to be further improved.

[0007] An efficient desulfurization method for preparing methanol from coke oven gas comprises the following steps:

[0008] S1, modifying Cu-BTC to prepare modified Cu-BTC, and using the modified Cu-BTC to desulfurize coke oven gas to obtain desulfurized coal char gas;

[0009] S2, separating and purifying the desulfurized coal tar gas to obtain carbon dioxide, carbon monoxide, hydrogen and separation gas;

[0010] S3, modifying ZSM-5 to prepare Cu-ZSM-5, and using the modified Cu-ZSM-5 to purify the separated gas for small molecules to obtain a mixed gas containing small molecule hydrocarbons such as methane;

[0011] S4, steam reforming the mixed gas to separate carbon monoxide and hydrogen;

[0012] S5. Prepare methanol using the carbon monoxide and hydrogen obtained in step S2 and step S4.

[0013] Further, in step S1, the modification operation includes the following steps:

[0014] A1, mixing a thiol compound, a carboxylic acid and Cu-BTC, dissolving the mixed powder in ethanol to obtain a uniform suspension, adding the suspension to a reactor for reaction, filtering, and drying to obtain a modified Cu-BTC precursor;

[0015] A2, taking n-octadecyltrichlorosilane and dissolving it in dichloromethane to prepare a saturated solution, mixing the modified Cu-BTC precursor and the n-octadecyltrichlorosilane solution and adding them to the reactor to react, after the reaction is completed, filtering and drying to obtain the modified Cu-BTC;

[0016] Furthermore, in step A1, the selected thiol compound is 3-mercaptopropionic acid, and the selected carboxylic acid is trichloroacetic acid, wherein the weight ratio of 3-mercaptopropionic acid, trichloroacetic acid and Cu-BTC is 6-8:2-4:1, the reactor temperature is set to 50-60°C, the reaction time is 16-24h, the rotation speed is 280r / min, the drying condition is vacuum drying, the temperature is 80°C, and it is dried to a constant weight of the modified Cu-BTC precursor; in step A2, the reactor temperature is set to 40-60°C, the reaction time is 12-18h, the drying condition is vacuum drying, the temperature is 80°C, and it is dried to a constant weight of the modified Cu-BTC precursor.

[0017] Furthermore, in step S1, coal gas desulfurization includes the following steps: mixing the modified Cu-BTC and titanium dioxide and placing them in a pressure vessel, irradiating them with ultraviolet rays, introducing coke oven gas thereinto, pressurizing them to 2.5-3.5 MPa, reacting for 3 hours, and collecting the gas to obtain desulfurized coal tar gas.

[0018] Reaction principle:

[0019] In the process of preparing the modified Cu-BTC precursor by the mixed reaction of 3-mercaptopropionic acid, trichloroacetic acid and Cu-BTC, 3-mercaptopropionic acid and trichloroacetic acid will introduce thiol groups and hydroxyl groups into Cu-BTC respectively. The former will enhance the adsorption capacity of the metal organic framework compound Cu-BTC for hydrogen sulfide, while the latter will reduce its adsorption capacity for carbon dioxide. In the process of preparing the modified Cu-BTC by surface modification of the modified Cu-BTC precursor with n-octadecyltrichlorosilane, n-octadecyltrichlorosilane will enhance the hydrophobicity of the surface of the modified Cu-BTC precursor and thereby reduce its adsorption capacity for small molecular hydrocarbons such as hydrogen and methane. Under the irradiation of ultraviolet rays, the semiconductor catalyst titanium dioxide will be excited by photons, thereby catalytically oxidizing the organic sulfide into inorganic sulfide, thereby achieving a better desulfurization effect.

[0020] Further, in step S2, the separation and purification operation includes the following steps:

[0021] B1, desulfurized coal tar gas is passed through monoethanolamine solution, CuCl-KCl complex solution and Matrimid5218-F2 membrane in sequence to remove carbon dioxide, carbon monoxide and hydrogen respectively;

[0022] B2, heating the CuCl-KCl complex solution and the monoethanolamine solution respectively to remove the absorbed carbon monoxide and carbon dioxide gases, and drying them with concentrated sulfuric acid;

[0023] B3. The hydrogen, carbon monoxide and carbon dioxide obtained from purifying coke oven gas are kept for future use.

[0024] Furthermore, in step B1, during the preparation of the CuCl-KCl complex solution, the concentration of the CuCl solution used is 1 mol / L, the concentration of the KCl solution is 1.5 mol / L, the volume ratio is 1:1, and the monoethanolamine solution is a saturated solution; in step B2, the heating temperature is 60° C., and the mass fraction of concentrated sulfuric acid is 98%.

[0025] Reaction principle:

[0026] Monoethanolamine solution and CuCl-KCl complex solution have extremely strong selectivity for carbon dioxide and carbon monoxide, which can be separated by simple heat treatment. Pure carbon dioxide and carbon monoxide can be obtained after purification with concentrated sulfuric acid. Matrimid 5218 membrane itself has extremely high selectivity for hydrogen. The selectivity of Matrimid 5218-F2 membrane obtained after fluorination will be further improved.

[0027] Furthermore, in step S3, the operation of absorbing the separated gas and removing the mixed gas after the ZSM-5 modification includes the following steps:

[0028] C1. Soak the ZSM-5 molecular sieve in a solution containing a certain concentration of copper ions for 16-24 hours to allow the copper ions to be fully exchanged. Take out the soaked ZSM-5, filter, wash and dry it;

[0029] C2. The dried sample is calcined at high temperature to obtain Cu-ZSM-5. After cooling, the coke oven gas separated by components is introduced at a constant temperature to absorb methane and other small molecular hydrocarbons.

[0030] C3. After heating and absorbing methane and other small molecule hydrocarbons, the Cu-ZSM-5 material is separated and collected for later use.

[0031] Furthermore, in step C1, the selected copper ion solution is Cu(NO3)2 solution, wherein the Cu(NO3)2 solution is a saturated solution; in step C2, the calcination operation includes: transferring the dried soaked ZSM-5 to the calcination, introducing nitrogen protection, raising the calcination furnace to 500-600°C at a rate of 10°C / min, keeping warm for 3-5h, stopping heating and cooling to 300-400°C, introducing the gas flow rate of the component-separated coke oven gas at 10-20L / h, and the residence time is 0.1-1 second; in step C3, the heating temperature is 600°C.

[0032] Reaction principle:

[0033] ZSM-5 is a zeolite molecular sieve with a specific pore structure and surface chemical properties. It has a certain adsorption capacity for methane and small molecular hydrocarbons. The selectivity of Cu-ZSM-5 obtained by soaking ZSM-5 in a Cu(NO3)2 solution and reacting it for small molecular hydrocarbons such as methane will be further improved, and after heat treatment, small molecular hydrocarbons such as methane can be quickly separated from the pores.

[0034] Further, in step S4, the separation operation after steam reforming includes the following steps:

[0035] D1, methane and other small molecular hydrocarbons are mixed with water vapor in a volume ratio of 2:1 and then introduced into the Ni / SiO 2 -Al 2 O 3 The catalyst is placed in a reaction vessel at a pressure of 1-3 MPa and a temperature of 850-950°C. After the reaction gas is cooled, it is again removed by Cu-ZSM-5 and then introduced into 98 wt% concentrated sulfuric acid for dehydration to obtain pure water gas;

[0036] D2. Use CuCl-KCl complex solution and Matrimid 5218-F2 membrane to remove carbon monoxide and hydrogen respectively, and introduce 98 wt % concentrated sulfuric acid for dehydration to obtain pure carbon monoxide and pure hydrogen, which are collected for later use.

[0037] Reaction principle:

[0038] In Ni / SiO 2 -Al 2 O 3 As a catalyst, under the conditions of pressure of 1-3MPa and temperature of 850-950℃, methane and other small molecule hydrocarbons can be steam reformed to generate raw gas carbon monoxide and hydrogen. The generated raw gas is passed through Cu-ZSM-5 for impurity removal to adsorb the unreacted methane and small molecule hydrocarbons, ensuring the effective progress of subsequent reactions.

[0039] Further, in step S5, the methanol preparation operation includes the following steps:

[0040] E1. Use ethylene glycol and deionized water to prepare a new coolant;

[0041] E2, using desulfurized coal tar gas purification and steam reforming of small molecular hydrocarbons such as methane to obtain carbon monoxide and hydrogen, which are mixed and compressed and then introduced into a methanol preparation tower to prepare crude methanol and collect waste gas, and the crude methanol is distilled to obtain refined methanol;

[0042] E3. Repeat the component separation operation in S2 for the waste gas, and use the collected hydrogen and carbon monoxide as reactants and carbon dioxide as a carbon source in proportion to introduce them into the methanol preparation device for secondary reaction, and the remaining waste is discharged as purge gas.

[0043] Furthermore, in step E1, the volume ratio of ethylene glycol to water is 1:1; in step E2, the volume ratio of carbon monoxide to hydrogen is 1:2, compressed to 3.2-3.8 MPa, the catalyst is a copper-based catalyst, the pressure in the tower is 5-10 MPa, the temperature in the tower is 200-300°C, and the outlet temperature is 280-300°C; in step E3, the volume ratio of hydrogen, carbon monoxide and carbon dioxide is 2:1:1.

[0044] Reaction principle:

[0045] The new coolant uses a mixture of ethylene glycol and water, which can lower the freezing point and increase the boiling point, allowing the coolant to work stably in a wider temperature range. The addition of ethylene glycol makes the mixed coolant less likely to freeze at low temperatures and less likely to boil at high temperatures, providing good temperature control capabilities; the exhaust gas is separated and then reacted using the S2 step, further improving the yield.

[0046] The present invention has the following beneficial effects:

[0047] 1. In the desulfurization process, the present invention uses dry separation instead of wet separation, so that the separation process has a relatively simple process flow, reduces the complex liquid processing link, makes the system more stable and easy to control, and does not use liquid medium in the separation process. Compared with the wet separation equipment, the alkaline liquid will not corrode, thereby extending the service life of the equipment and reducing the maintenance and replacement costs; in the desulfurization process, the modified Cu-BTC prepared by modifying Cu-BTC and titanium dioxide are mixed for removal, which not only removes the inorganic sulfur in the coke oven gas, but also selectively oxidizes the organic sulfur in the coke oven gas, so that the sulfur removal is more thorough; Cu -BTC is modified to prepare modified Cu-BTC. First, thiol groups and hydroxyl groups are introduced into Cu-BTC through 3-mercaptopropionic acid and trichloroacetic acid. The former will enhance the adsorption capacity of the metal organic framework compound Cu-BTC for hydrogen sulfide, while the latter will reduce its adsorption capacity for carbon dioxide. In the process of preparing modified Cu-BTC by surface modification of the modified Cu-BTC precursor with n-octadecyltrichlorosilane, n-octadecyltrichlorosilane will enhance the hydrophobicity of the surface of the modified Cu-BTC precursor and thus reduce its adsorption capacity for small molecular hydrocarbons such as hydrogen and methane, making dry separation more selective.

[0048] 2. In the preparation process of methanol, the present invention uses monoethanolamine solution, CuCl-KCl complex solution and Matrimid 5218-F2 membrane to remove carbon dioxide, carbon monoxide and hydrogen respectively. Monoethanolamine solution and CuCl-KCl complex solution have strong selectivity for carbon dioxide and carbon monoxide, which can be separated by simple heat treatment. Matrimid The 5218-F2 membrane has extremely high selectivity for hydrogen. By separating the components of coke oven gas, raw gas can be added according to the preparation requirements in the subsequent methanol preparation process, so that the reaction can be completed and the purity of the product methanol can be further improved. After the ZSM-5 is modified to prepare Cu-ZSM-5, it can absorb small molecular hydrocarbons such as methane after cooling in the same device. After heating again, small molecular hydrocarbons such as methane can be separated, and then steam reforming can be performed to obtain the raw gas required for methanol preparation. The selectivity of Cu-ZSM-5 after the ZSM-5 modification to small molecular hydrocarbons such as methanol is further improved, ensuring the purity of small molecular hydrocarbons such as methane. Steam reforming of small molecular hydrocarbons such as methane also reduces side reactions in the preparation of methanol and increases the concentration of product methanol.

[0049] 3. In the preparation process of methanol, the instruments and reagents used for the separation of the components of coke oven gas and exhaust gas are consistent; unified instruments can bring standardized operation procedures and data processing methods, which are beneficial to quality control and quality assurance. At the same time, operators can more easily become familiar with and master the unified operation procedures, thereby reducing the possibility of operating errors, and can also more easily achieve the centralization of technical support and maintenance services; large-scale procurement of instruments of the same type may lead to reduced procurement costs and maintenance costs. At the same time, maintenance and training for instruments of the same type are also more convenient and economical; in industrial production, the use of consistent reagents can simplify the process of process validation and related approval processes. This includes verifying the scalability of the reaction and determining the resources required in production to ensure compliance with regulations and quality standards; consistent use of reagents can obtain cost advantages through bulk procurement and long-term cooperative relationships, and can also reduce experimental variables and optimize process conditions to reduce production costs and improve production efficiency; consistent use of reagents can reduce the number of variables in production, making production conditions easier to control and optimize, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 The present invention is a flow chart of a highly efficient desulfurization method for preparing methanol from coke oven gas. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Example 1

[0054] This embodiment provides a high-efficiency desulfurization method for preparing methanol from coke oven gas, comprising the following steps:

[0055] S1. Coke oven gas desulfurization

[0056] The weight ratio of 3-mercaptopropionic acid, trichloroacetic acid and Cu-BTC is 6:2:1, the mixed powder is dissolved in ethanol and mixed to obtain a uniform suspension, the suspension is added to a reactor, the reactor temperature is 50°C, the reaction time is 16h, the rotation speed is 280r / min, and the modified Cu-BTC precursor is obtained by suction filtration, and the Cu-BTC precursor is vacuum dried at 80°C until the modified Cu-BTC precursor has a constant weight;

[0057] n-octadecyltrichlorosilane was dissolved in dichloromethane to prepare a saturated solution, the Cu-BTC precursor and the n-octadecyltrichlorosilane solution were mixed and added into a reactor, the reactor temperature was 40°C, the reaction time was 12h, after the reaction was completed, the modified Cu-BTC was filtered to obtain the modified Cu-BTC, the modified Cu-BTC was vacuum dried at 80°C until the modified Cu-BTC was constant weight;

[0058] The modified Cu-BTC and titanium dioxide are mixed and placed in a pressure vessel, irradiated with ultraviolet rays, and coke oven gas is introduced into the vessel, pressurized to 2.5 MPa, reacted for 3 hours, and the gas is collected to obtain desulfurized coal tar gas.

[0059] S2. Desulfurized coal tar gas purification

[0060] A CuCl solution with a concentration of 1 mol / L and a KCl solution with a concentration of 1.5 mol / L are mixed in a volume ratio of 1:1 to obtain a CuCl-KCl complex solution;

[0061] The desulfurized coal tar gas was passed through saturated monoethanolamine solution, CuCl-KCl complex solution and Matrimid5218-F2 membrane in sequence to remove carbon dioxide, carbon monoxide and hydrogen respectively;

[0062] The CuCl-KCl complex solution and the monoethanolamine solution were heated to 60° C. respectively to remove the absorbed carbon monoxide and carbon dioxide gases, and dried by 98 wt % concentrated sulfuric acid;

[0063] The hydrogen, carbon monoxide and carbon dioxide obtained from the purified desulfurized coal tar gas are collected for future use.

[0064] S3, removal of methane and other small molecule hydrocarbons

[0065] The ZSM-5 molecular sieve was immersed in a saturated Cu(NO3)2 solution for 16 hours to allow the copper ions to be fully exchanged, and the immersed ZSM-5 was taken out, filtered, washed and dried;

[0066] After the dried soaked ZSM-5 was transferred to the calcining furnace, nitrogen was introduced for protection. The calcining furnace was heated to 500°C at a rate of 10°C / min, kept warm for 3h, and then cooled to 300°C after stopping heating. The gas flow rate of the separated coke oven gas was 10L / h, and the residence time was 0.1 second.

[0067] The Cu-ZSM-5 material after absorbing methane and other small molecule hydrocarbons is heated to 600° C., and the methane and other small molecule hydrocarbons are separated and collected for later use.

[0068] S4, steam reforming of methane and other small hydrocarbons

[0069] Small molecular hydrocarbons such as methane are mixed with water vapor in a volume ratio of 2:1 and then introduced into the Ni / SiO 2 -Al 2 O 3 The catalyst is placed in a reaction vessel at a pressure of 1 MPa and a temperature of 850°C. After the reaction gas is cooled, it is again removed by Cu-ZSM-5 and then introduced into 98 wt% concentrated sulfuric acid for dehydration to obtain pure water gas.

[0070] CuCl-KCl complex solution and Matrimid 5218-F2 membrane were used to remove carbon monoxide and hydrogen respectively, and 98 wt % concentrated sulfuric acid was introduced for dehydration to obtain pure carbon monoxide and pure hydrogen respectively.

[0071] S5. Preparation of methanol

[0072] A new coolant is prepared using ethylene glycol and water in a volume ratio of 1:1;

[0073] Carbon monoxide and hydrogen obtained by purifying desulfurized coal tar gas and steam reforming small molecular hydrocarbons such as methane are mixed and compressed to 3.2MPa in a volume ratio of 1:2 and introduced into a methanol preparation tower with a pressure of 5MPa, a temperature of 200°C and a copper-based catalyst to prepare crude methanol and collect waste gas. The crude methanol is distilled to obtain refined methanol;

[0074] The waste gas repeats the component separation operation in S2, and the collected hydrogen and carbon monoxide are used as reactants, and carbon dioxide is used as a carbon source in a volume ratio of 2:1:1 to pass into the methanol preparation device for secondary reaction, and the remaining waste gas is discharged as purge gas.

[0075] Example 2

[0076] This embodiment provides a high-efficiency desulfurization method for preparing methanol from coke oven gas, comprising the following steps:

[0077] S1. Coke oven gas desulfurization

[0078] The weight ratio of 3-mercaptopropionic acid, trichloroacetic acid and Cu-BTC is 7:3:1, the mixed powder is dissolved in ethanol and mixed to obtain a uniform suspension, the suspension is added to a reactor, the reactor temperature is 55°C, the reaction time is 20h, the rotation speed is 280r / min, and the modified Cu-BTC precursor is obtained by suction filtration. The Cu-BTC precursor is vacuum dried at 80°C until the modified Cu-BTC precursor has a constant weight;

[0079] Dissolve n-octadecyltrichlorosilane in dichloromethane to prepare a saturated solution, mix the Cu-BTC precursor and the n-octadecyltrichlorosilane solution and add them into a reactor. The reactor temperature is 50°C and the reaction time is 15h. After the reaction is completed, filter to obtain modified Cu-BTC. The modified Cu-BTC is vacuum dried at 80°C until the modified Cu-BTC has a constant weight.

[0080] The modified Cu-BTC and titanium dioxide are mixed and placed in a pressure vessel, irradiated with ultraviolet rays, and coke oven gas is introduced into the vessel, pressurized to 3.0 MPa, reacted for 3 hours, and the gas is collected to obtain desulfurized coal tar gas.

[0081] S2. Desulfurized coal tar gas purification

[0082] A CuCl solution with a concentration of 1 mol / L and a KCl solution with a concentration of 1.5 mol / L are mixed in a volume ratio of 1:1 to obtain a CuCl-KCl complex solution;

[0083] The desulfurized coal tar gas was passed through saturated monoethanolamine solution, CuCl-KCl complex solution and Matrimid5218-F2 membrane in sequence to remove carbon dioxide, carbon monoxide and hydrogen respectively;

[0084] The CuCl-KCl complex solution and the monoethanolamine solution were heated to 60° C. respectively to remove the absorbed carbon monoxide and carbon dioxide gases, and dried by 98 wt % concentrated sulfuric acid;

[0085] The hydrogen, carbon monoxide and carbon dioxide obtained from the purified desulfurized coal tar gas are collected for future use.

[0086] S3, removal of methane and other small molecule hydrocarbons

[0087] The ZSM-5 molecular sieve was immersed in a saturated Cu(NO3)2 solution for 20 hours to allow the copper ions to be fully exchanged, and the immersed ZSM-5 was taken out, filtered, washed and dried;

[0088] After the dried soaked ZSM-5 was transferred to the calcining furnace, nitrogen was introduced for protection. The calcining furnace was heated to 550°C at a rate of 10°C / min, kept warm for 4 hours, and then cooled to 350°C after stopping heating. The gas flow rate of the separated coke oven gas was 15L / h, and the residence time was 0.6 seconds.

[0089] The Cu-ZSM-5 material after absorbing methane and other small molecule hydrocarbons is heated to 600° C., and the methane and other small molecule hydrocarbons are separated and collected for later use.

[0090] S4, steam reforming of methane and other small hydrocarbons

[0091] Small molecular hydrocarbons such as methane are mixed with water vapor in a volume ratio of 2:1 and then introduced into the Ni / SiO 2 -Al 2 O 3 The catalyst is placed in a reaction vessel at a pressure of 2 MPa and a temperature of 900°C. After the reaction gas is cooled, it is again removed by Cu-ZSM-5 and then introduced into 98 wt% concentrated sulfuric acid for dehydration to obtain pure water gas.

[0092] CuCl-KCl complex solution and Matrimid 5218-F2 membrane were used to remove carbon monoxide and hydrogen respectively, and 98 wt % concentrated sulfuric acid was introduced for dehydration to obtain pure carbon monoxide and pure hydrogen respectively.

[0093] S5. Preparation of methanol

[0094] A new coolant is prepared using ethylene glycol and water in a volume ratio of 1:1;

[0095] Carbon monoxide and hydrogen obtained by purifying desulfurized coal tar gas and steam reforming small molecular hydrocarbons such as methane are mixed and compressed to 3.5MPa in a volume ratio of 1:2 and introduced into a methanol preparation tower with a pressure of 7.5MPa and a temperature of 250°C in the tower and a copper-based catalyst to prepare crude methanol and collect waste gas. The crude methanol is distilled to obtain refined methanol;

[0096] The waste gas repeats the component separation operation in S2, and the collected hydrogen and carbon monoxide are used as reactants, and carbon dioxide is used as a carbon source in a volume ratio of 2:1:1 to pass into the methanol preparation device for secondary reaction, and the remaining waste gas is discharged as purge gas.

[0097] Example 3

[0098] This embodiment provides a high-efficiency desulfurization method for preparing methanol from coke oven gas, comprising the following steps:

[0099] S1. Coke oven gas desulfurization

[0100] The weight ratio of 3-mercaptopropionic acid, trichloroacetic acid and Cu-BTC is 8:4:1, the mixed powder is dissolved in ethanol and mixed to obtain a uniform suspension, the suspension is added to a reactor, the reactor temperature is 60°C, the reaction time is 24h, the rotation speed is 280r / min, and the modified Cu-BTC precursor is obtained by suction filtration, and the Cu-BTC precursor is vacuum dried at 80°C until the modified Cu-BTC precursor has a constant weight;

[0101] Dissolve n-octadecyltrichlorosilane in dichloromethane to prepare a saturated solution, mix the Cu-BTC precursor and the n-octadecyltrichlorosilane solution and add them into a reactor. The reactor temperature is 60°C and the reaction time is 18h. After the reaction is completed, filter to obtain modified Cu-BTC. The modified Cu-BTC is vacuum dried at 80°C until the modified Cu-BTC has a constant weight.

[0102] The modified Cu-BTC and titanium dioxide are mixed and placed in a pressure vessel, irradiated with ultraviolet rays, and coke oven gas is introduced into the vessel, pressurized to 3.5 MPa, reacted for 3 hours, and the gas is collected to obtain desulfurized coal tar gas.

[0103] S2. Desulfurized coal tar gas purification

[0104] A CuCl solution with a concentration of 1 mol / L and a KCl solution with a concentration of 1.5 mol / L are mixed in a volume ratio of 1:1 to obtain a CuCl-KCl complex solution;

[0105] The desulfurized coal tar gas was passed through saturated monoethanolamine solution, CuCl-KCl complex solution and Matrimid5218-F2 membrane in sequence to remove carbon dioxide, carbon monoxide and hydrogen respectively;

[0106] The CuCl-KCl complex solution and the monoethanolamine solution were heated to 60° C. respectively to remove the absorbed carbon monoxide and carbon dioxide gases, and dried by 98 wt % concentrated sulfuric acid;

[0107] The hydrogen, carbon monoxide and carbon dioxide obtained from the purified desulfurized coal tar gas are collected for future use.

[0108] S3, removal of methane and other small molecule hydrocarbons

[0109] The ZSM-5 molecular sieve was immersed in a saturated Cu(NO3)2 solution for 24 hours to allow the copper ions to be fully exchanged, and the immersed ZSM-5 was taken out, filtered, washed and dried;

[0110] After the dried soaked ZSM-5 was transferred to the calcining furnace, nitrogen was introduced for protection. The calcining furnace was heated to 600°C at a rate of 10°C / min, kept warm for 5 hours, and then cooled to 400°C after stopping heating. The gas flow rate of the separated coke oven gas was 20L / h, and the residence time was 1 second.

[0111] The Cu-ZSM-5 material after absorbing methane and other small molecule hydrocarbons is heated to 600° C., and the methane and other small molecule hydrocarbons are separated and collected for later use.

[0112] S4, steam reforming of methane and other small hydrocarbons

[0113] Small molecular hydrocarbons such as methane are mixed with water vapor in a volume ratio of 2:1 and then introduced into the Ni / SiO 2 -Al 2 O 3 The catalyst is placed in a reaction vessel with a pressure of 3 MPa and a temperature of 950°C. After the reaction gas is cooled, it is again removed by Cu-ZSM-5 and then introduced into 98 wt% concentrated sulfuric acid for dehydration to obtain pure water gas.

[0114] CuCl-KCl complex solution and Matrimid 5218-F2 membrane were used to remove carbon monoxide and hydrogen respectively, and 98 wt % concentrated sulfuric acid was introduced for dehydration to obtain pure carbon monoxide and pure hydrogen respectively.

[0115] S5. Preparation of methanol

[0116] A new coolant is prepared using ethylene glycol and water in a volume ratio of 1:1;

[0117] Carbon monoxide and hydrogen obtained by purifying desulfurized coal tar gas and steam reforming small molecular hydrocarbons such as methane are mixed and compressed to 3.8MPa in a volume ratio of 1:2 and introduced into a methanol preparation tower with a pressure of 10MPa, a temperature of 300°C and a copper-based catalyst to prepare crude methanol and collect waste gas. The crude methanol is distilled to obtain refined methanol;

[0118] The waste gas repeats the component separation operation in S2, and the collected hydrogen and carbon monoxide are used as reactants, and carbon dioxide is used as a carbon source in a volume ratio of 2:1:1 to pass into the methanol preparation device for secondary reaction, and the remaining waste gas is discharged as purge gas.

[0119] Comparative Example 1

[0120] The difference between this comparative example and Example 3 is that step S1 is omitted and unmodified Cu-BTC is used to adsorb hydrogen sulfide.

[0121] Comparative Example 2

[0122] The difference between this comparative example and Example 3 is that in step S3, unmodified ZSM-5 is used to adsorb small molecular hydrocarbons such as methane.

[0123] Performance Test:

[0124] With reference to standard YB / T 4496-2015 "Gas chromatography method for determination of hydrogen sulfide content in coke oven gas", the content of hydrogen sulfide in the desulfurized coal coke prepared by Example 1-3 and Comparative Example 1-2 was determined; with reference to GB / T 28901-2012 "Gas chromatography analysis method for coke oven gas components", the components of the carbon monoxide and hydrogen mixed gas obtained by purification of desulfurized coal coke and steam reforming of small molecular hydrocarbons such as methane in Example 1-3 and Comparative Example 1-2 were analyzed; with reference to GB / T 338-2011 "Industrial methanol", the performance of the methanol prepared by Example 1-3 and Comparative Example 1-2 was tested, and the test results are shown in Table 1-3.

[0125] Table 1. Hydrogen sulfide content in desulfurized coal tar gas

[0126]

[0127] Table 2. Analysis of mixed gas components

[0128]

[0129] Table 3. Methanol performance test

[0130]

[0131]

[0132] Comparing the data in Table 1 above, the concentration of hydrogen sulfide in the desulfurized coal tar gas treated with the modified Cu-BTC is reduced to 0.25%, while the concentration of the desulfurized coal tar gas treated with the unmodified Cu-BTC is 1.03%, which is an improvement of 412%; comparing the data in Table 2 above, the methane concentration of the gas treated with Cu-ZSM-5 modified by ZSM-5 is 0.10%, while the methane concentration after treatment with ZSM-5 is 0.54%, which is an improvement of 540%; comparing the data in Table 3 above, the pure gas obtained by treating the coke oven gas with the modified material can effectively reduce the influence of small molecular hydrocarbons such as hydrogen sulfide and methane in the reaction, so that the produced methanol meets the industrial grade requirements.

[0133] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0134] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0135] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A highly efficient desulfurization method for preparing methanol from coke oven gas, characterized in that: The following steps are involved: S1, modifying Cu-BTC to prepare modified Cu-BTC, and using the modified Cu-BTC to desulfurize coke oven gas to obtain desulfurized coal coke gas; S2, separating and purifying the desulfurized coal tar gas to obtain carbon dioxide, carbon monoxide, hydrogen and separation gas; S3, modifying ZSM-5 to prepare Cu-ZSM-5, and using the modified Cu-ZSM-5 to purify the separated gas for small molecules to obtain a mixed gas containing small molecule hydrocarbons such as methane; S4, steam reforming the mixed gas to separate carbon monoxide and hydrogen; S5. Prepare methanol using the carbon monoxide and hydrogen obtained in step S2 and step S4.

2. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 1, characterized in that: In step S1, the modification operation includes the following steps: A1, mixing a thiol compound, a carboxylic acid and Cu-BTC, dissolving the mixed powder in ethanol to obtain a uniform suspension, adding the suspension to a reactor for reaction, filtering, and drying to obtain a modified Cu-BTC precursor; A2. Dissolve n-octadecyltrichlorosilane in dichloromethane to prepare a saturated solution. Mix the modified Cu-BTC precursor and the n-octadecyltrichlorosilane solution and add them into a reactor to react. After the reaction is completed, filter and dry to obtain the modified Cu-BTC.

3. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 2, characterized in that: In step A1, the selected thiol compound is 3-mercaptopropionic acid, and the selected carboxylic acid is trichloroacetic acid, wherein the weight ratio of 3-mercaptopropionic acid, trichloroacetic acid and Cu-BTC is 6-8:2-4:1, the reactor temperature is set to 50-60°C, the reaction time is 16-24h, the rotation speed is 280r / min, the drying condition is vacuum drying, the temperature is 80°C, and it is dried to a constant weight of the modified Cu-BTC precursor; in step A2, the reactor temperature is set to 40-60°C, the reaction time is 12-18h, the drying condition is vacuum drying, the temperature is 80°C, and it is dried to a constant weight of the modified Cu-BTC precursor.

4. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 1, characterized in that: In step S1, coal gas desulfurization includes the following steps: mixing modified Cu-BTC and titanium dioxide and placing them in a pressure vessel, irradiating them with ultraviolet rays, introducing coke oven gas into the pressure vessel, pressurizing it to 2.5-3.5 MPa, reacting for 3 hours, and collecting the gas to obtain desulfurized coal tar gas.

5. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 1, characterized in that: In step S2, the separation and purification comprises the following steps: B1, desulfurized coal tar gas is passed through monoethanolamine solution, CuCl-KCl complex solution and Matrimid5218-F2 membrane in sequence to remove carbon dioxide, carbon monoxide and hydrogen respectively; B2, heating the CuCl-KCl complex solution and the monoethanolamine solution respectively to remove the absorbed carbon monoxide and carbon dioxide gases, and drying them with concentrated sulfuric acid; B3. The hydrogen, carbon monoxide and carbon dioxide obtained from the purified desulfurized coal tar gas are collected for future use.

6. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 4, characterized in that: In step B1, during the preparation of the CuCl-KCl complex solution, the concentration of the CuCl solution used is 1 mol / L, the concentration of the KCl solution is 1.5 mol / L, the volume ratio is 1:1, and the monoethanolamine solution is a saturated solution; in step B2, the heating temperature is 60° C., and the mass fraction of concentrated sulfuric acid is 98%.

7. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 1, characterized in that: In step S3, the operation of absorbing the separated gas and removing the mixed gas after the ZSM-5 modification includes the following steps: C1. Soak the ZSM-5 molecular sieve in a solution containing a certain concentration of copper ions for 16-24 hours to allow the copper ions to be fully exchanged. Take out the soaked ZSM-5, filter, wash and dry it; C2. The dried sample is calcined at high temperature to obtain Cu-ZSM-5. After cooling, the coke oven gas separated by components is introduced at a constant temperature to absorb methane and other small molecular hydrocarbons. C3. After heating and absorbing methane and other small molecule hydrocarbons, the Cu-ZSM-5 material is separated and collected for later use.

8. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 6, characterized in that: In step C1, the copper ion solution selected in this experiment is Cu(NO3)2 solution, wherein the Cu(NO3)2 solution is a saturated solution; In step C2, the calcination operation includes: transferring the dried soaked ZSM-5 to the calcination furnace, introducing nitrogen protection, raising the temperature of the calcination furnace to 500-600°C at a rate of 10°C / min, keeping warm for 3-5h, stopping heating and cooling to 300-400°C, introducing the gas flow rate of the component-separated coke oven gas at 10-20L / h, and the residence time is 0.1-1 second; in step C3, the heating temperature is 600°C.

9. The high-efficiency desulfurization method for preparing methanol from coke oven gas according to claim 1, characterized in that: In step S4, the separation operation after steam reforming includes the following steps: D1. Mix small molecular hydrocarbons such as methane and water vapor in a volume ratio of 2:1 and introduce them into a reaction vessel with a Ni / SiO2-Al2O3 catalyst, a pressure of 1-3 MPa, and a temperature of 850-950°C. After the reaction gas is cooled, it is again removed by Cu-ZSM-5 and then introduced into 98wt% concentrated sulfuric acid for dehydration to obtain pure water gas; D2. Use CuCl-KCl complex solution and Matrimid 5218-F2 membrane to remove carbon monoxide and hydrogen respectively, and introduce 98 wt % concentrated sulfuric acid for dehydration to obtain pure carbon monoxide and pure hydrogen, which are collected for later use.

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