A system and method for preparing carbon monoxide by dry reforming of carbon dioxide and methane-containing gas

Abstract

The present invention relates to the field of carbon monoxide production, and more particularly to a system and method for producing carbon monoxide by dry reforming carbon dioxide and methane-containing gas. The system comprises a sequentially connected raw gas pretreatment module, a dry reforming module, and a carbon monoxide purification module. The raw gas pretreatment module is connected to an external gas source and is used to mix and purify the introduced raw gas. The raw gas pretreatment module comprises a mixing unit and several purification units. The mixing unit is used to mix different raw gases, and the purification unit is used to remove impurities in the raw gas. The dry reforming module is used to provide an environment for the dry reforming reaction for the purified raw gas. The carbon monoxide purification module is used to purify carbon monoxide from the gas generated by the reaction in the dry reforming module. The present invention can save energy and reduce consumption, reduce emissions, and achieve resource utilization of carbon dioxide by net consuming greenhouse gas carbon dioxide.

Description

Technical Field

[0001] The present invention relates to the field of carbon monoxide preparation, and in particular to a system and method for preparing carbon monoxide by dry reforming carbon dioxide and methane-containing gas. Background Art

[0002] In the chemical industry, carbon monoxide is the foundation of carbon chemistry and a key raw material for the synthesis of a range of basic organic chemical products and intermediates (such as alcohols, acids, anhydrides, esters, aldehydes, ethers, amides, and acyl chlorides). Carbon dioxide is a major greenhouse gas and the primary culprit for global warming, but it is also a carbon resource that can be utilized. However, the current utilization rate of carbon dioxide is only about 1%.

[0003] Methane-CO2 dry reforming is a methane-to-syngas process that can recycle greenhouse gases and effectively reduce CO2 emissions. It provides a clean and efficient conversion pathway for natural gas, biogas, coke oven gas, and other gases. The production of carbon monoxide from CO2 via methane dry reforming is an important research area.

[0004] Patent document CN102732324A discloses a method for producing carbon monoxide from carbon-containing feedstocks and the resulting products. This method uses solid carbon as the feedstock and gasifies the solid carbon in an entrained flow using oxygen, carbon dioxide, and superheated steam as gasifiers to produce carbon monoxide gas. The entire process requires equipment such as an oxygen generator, a solid carbon pretreatment unit, and a crude gas purification unit, resulting in a complex and expensive investment. The high-temperature crude gas is directly quenched with water, resulting in significant energy waste. The introduction of oxygen and superheated steam results in high energy consumption.

[0005] Patent document CN112758932A discloses an apparatus and method for producing carbon monoxide using hydrogen and carbon dioxide as raw materials. This method utilizes reverse water-gas shift reaction in a triple-bed reactor through the circulation of an iron-based oxygen carrier. The reaction requires the use of a solid oxygen carrier circulating through the three reactors, resulting in a complex operation. The gas exiting the hydrogen reactor contains water and dust, which can easily cause blockage.

[0006] Patent document CN1336322A discloses a method for producing high-carbon monoxide gas. This method involves feeding light oil, liquefied gas, or refinery gas, along with water vapor and carbon dioxide, into a reaction bed containing a hydrocarbon steam reforming catalyst for a one-step steam reforming reaction. A high-carbon monoxide gas consisting of carbon monoxide and hydrogen is then separated from the reformed gas. The introduction of water vapor as a reforming agent in this method affects the equilibrium carbon monoxide concentration, reducing the carbon monoxide yield and increasing the energy consumption of the device.

[0007] Patent document CN102838116A discloses a method for producing carbon monoxide from coke oven gas and carbon dioxide. The method uses a reforming / reverse conversion bifunctional catalyst and a reverse conversion catalyst in combination, and adopts a three-stage conversion process to achieve carbon monoxide conversion of coke oven gas and carbon dioxide. Multiple catalysts are required. Since the optimal conditions of different reactions and catalysts are different, all reactions are carried out in the same reactor. Parameters such as temperature need to be adjusted according to different reaction stages. It is difficult to control each reaction stage in the optimal reaction state, resulting in low preparation efficiency. During the reaction process, the carbon dioxide and hydrogen and other residual gases (CO2, H2, methane, etc.) after separation of the product carbon monoxide are recycled to the raw material, which will cause the ratio of CO2 to H2 and CH4 in the reactor to be uncontrollable, making it difficult to reach the chemical reaction equilibrium point. That is, in the reaction gas formed by mixing the recycled gas and the raw material gas, the ratio between CO2 and H2 and CH4 is unbalanced, making it difficult to achieve chemical reaction equilibrium, affecting the normal progress of the reaction. In addition, the method only produces carbon monoxide from a single raw material, coke oven gas and carbon dioxide, and the raw material source is relatively single. Summary of the Invention

[0008] In order to improve the deficiencies of the prior art, the present invention provides a system and method for preparing carbon monoxide by dry reforming carbon dioxide and methane-containing gas, wherein the raw gas is carbon dioxide-rich gas and methane-containing gas (natural gas, shale gas, coalbed methane, coke oven gas, raw coal gas, biogas, refinery gas, etc.), based on a dry reforming catalyst suitable for high carbon dioxide reaction conditions, and carbon monoxide gas is prepared through a dry reforming process of methane and carbon dioxide.

[0009] The object of the present invention is achieved through the following technical solutions:

[0010] A system for preparing carbon monoxide by dry reforming carbon dioxide and methane-containing gas comprises a raw gas pretreatment module, a dry reforming module and a carbon monoxide purification module which are connected in sequence.

[0011] The raw gas pretreatment module is connected to an external gas source (including a methane gas pipeline and a carbon dioxide-rich gas pipeline) and is used to mix and purify the imported raw gas. The raw gas pretreatment module includes a mixing unit and several purification units. The mixing unit is used to mix different raw gases, and the purification unit is used to remove impurities in the raw gas.

[0012] Wherein, the raw gas includes methane-containing gas and carbon dioxide-rich gas.

[0013] The dry reforming module is used to provide an environment for dry reforming reaction for the purified raw gas. The dry reforming module includes a reaction unit and a heating unit. The reaction unit is used to carry out dry reforming reaction. The heating unit is used to burn fuel to provide the reaction unit with the temperature required for the reaction. The fuel includes methane-containing gas from the same source as the raw gas.

[0014] The carbon monoxide purification module is used to purify carbon monoxide from the gas generated by the reaction in the dry reforming module.

[0015] According to an embodiment of the present invention, the carbon monoxide purification module is further used to introduce the remaining gas after carbon monoxide purification (hereinafter referred to as carbon monoxide purified residual gas) as fuel gas into the dry reforming module.

[0016] According to an embodiment of the present invention, the purification unit includes a combination of one or more of a deoiling unit, a naphthalene removal unit, a rough desulfurization unit, a fine desulfurization unit, a dehydration unit, and a pre-reforming unit.

[0017] Preferably, when there are multiple purification units, different purification units are connected in sequence, and the connection order is arranged according to actual needs.

[0018] Preferably, the dry reforming module is a dry reforming converter, such as a tubular furnace reactor for natural gas steam reforming.

[0019] According to an embodiment of the present invention, the heating unit is used to burn methane-containing gas and / or carbon monoxide purified residual gas.

[0020] Preferably, the methane-containing gas in the heating unit and the methane-containing gas in the raw gas are transported through the same gas pipeline, that is, the heating unit and the raw gas pretreatment module share a set of methane-containing gas transportation pipelines. Compared with the existing dry reforming reaction in which the raw gas and the fuel gas are the same or different and are transported through different pipelines, this can effectively reduce costs.

[0021] According to an embodiment of the present invention, a catalyst is provided in the dry reforming module.

[0022] According to an embodiment of the present invention, the catalyst is a Ni-based catalyst, the carrier of the catalyst is selected from a composite oxide carrier, the Ni content in the Ni-based catalyst is 10-15%, preferably the Ni content in the Ni-based catalyst is 12-14%, for example, 12%, 13%, 14%.

[0023] Preferably, the composite oxide support comprises MgO and γ-Al2O3. Preferably, the molar ratio of MgO and γ-Al2O3 is (0.5-2):1. Further, the molar ratio of MgO and γ-Al2O3 is (0.8-1.5):1, for example, 0.6:1, 0.9:1, 1:1, 1.2:1, 1.8:1.

[0024] According to an embodiment of the present invention, the catalyst further comprises an auxiliary agent.

[0025] Preferably, the additive includes precious metals and / or rare earth metals, the precious metals include at least one of gold, silver, and platinum, and the rare earth metals include at least one of scandium, yttrium, lanthanum, cerium, praseodymium, and neodymium.

[0026] Preferably, the dry reforming module is further provided with a temperature adjustment unit, and the temperature adjustment unit is used to adjust the reaction temperature in the dry reforming module.

[0027] Preferably, the dry reforming module is further provided with a pressure adjustment unit, and the pressure adjustment unit is used to adjust the reaction pressure in the dry reforming module.

[0028] Preferably, the dry reforming module is further provided with an airspeed adjustment unit, and the airspeed adjustment unit is used to adjust the airspeed in the dry reforming module.

[0029] According to an embodiment of the present invention, a preheating unit is further provided between the dry reforming module and the raw gas pretreatment module. The preheating unit is used to preheat the gas pretreated by the raw gas pretreatment module. The preheating unit is, for example, a heat exchanger.

[0030] According to an embodiment of the present invention, a pressure adjustment unit is further provided between the raw gas pretreatment module and the preheating unit, and the pressure adjustment unit is used to adjust the pressure of the mixed gas; for example, the pressure adjustment unit is a compressor.

[0031] According to an embodiment of the present invention, a heat recovery unit is further provided between the dry reforming module and the carbon monoxide purification module, and the heat recovery unit is used to recover heat from the gas generated by the reaction in the dry reforming module.

[0032] According to an embodiment of the present invention, a steam-water separation unit is provided between the heat recovery unit and the carbon monoxide purification module. The steam-water separation unit is used to remove moisture from the gas generated by the reaction. Preferably, the steam-water separation unit is a gas-liquid separation tank.

[0033] According to an embodiment of the present invention, a carbon dioxide recovery unit is further provided between the steam-water separation unit and the carbon monoxide purification module, and the carbon dioxide recovery unit is used to recover carbon dioxide in the gas generated by the reaction.

[0034] According to an embodiment of the present invention, the carbon dioxide recovery unit is connected to the raw gas pretreatment module, and is used to introduce high-concentration carbon dioxide into the raw gas pretreatment module as carbon dioxide-rich gas.

[0035] According to an embodiment of the present invention, the purification unit includes a rough desulfurization unit and a fine desulfurization unit. The rough desulfurization unit is provided at the feed inlet of the methane-containing gas and is used to remove inorganic sulfur from the methane-containing gas.

[0036] According to an embodiment of the present invention, the fine desulfurization unit is connected to the mixing unit and is used to perform fine desulfurization on the mixed raw gas.

[0037] The present invention also provides a method for preparing carbon monoxide using the above system, comprising the following steps:

[0038] 1) mixing methane-containing gas and carbon dioxide-containing gas, and purifying the mixed gas to obtain purified gas;

[0039] 2) adding the purified gas to the dry reforming module for reaction to obtain a reaction gas;

[0040] 3) Separate carbon monoxide from the reaction gas.

[0041] According to an embodiment of the present invention, step 1) further comprises the following step: adding methane-containing gas as fuel to the heating unit of the dry reforming module for combustion to provide the temperature required for the reaction.

[0042] According to an embodiment of the present invention, after step 2) and before step 3), the process further comprises the following step: removing carbon dioxide gas from the reaction gas to obtain recovered carbon dioxide.

[0043] Preferably, the carbon dioxide is removed by using conventional decarbonization processes in the art, including MDEA decarbonization, pressure swing adsorption decarbonization, and NHD decarbonization.

[0044] According to an embodiment of the present invention, step 2) further includes the following step: introducing the recovered carbon dioxide gas as carbon dioxide-containing gas into a raw gas pretreatment module.

[0045] According to an embodiment of the present invention, after step 2) and before removing carbon dioxide, the following step is further included: recovering heat in the reaction gas.

[0046] According to an embodiment of the present invention, after recovering the heat in the reaction gas and before removing the carbon dioxide, the following step is further included: removing moisture from the gas, for example, introducing the gas into a gas-liquid separation tank for water separation.

[0047] According to an embodiment of the present invention, in the carbon dioxide-containing gas and the methane-containing gas in step 1), the molar ratio of carbon dioxide to the total hydrocarbon carbon number is 0.1 to 5.5. Preferably, the molar ratio of carbon dioxide to the total hydrocarbon carbon number is 0.1 to 4.0, 0.3 to 4.0, 0.9 to 3.6, 1.0 to 3.0, 1.2 to 2.5, for example, 1.66, 2.74, or 3.2.

[0048] Preferably, the total hydrocarbon carbon number refers to the total carbon number of all hydrocarbon substances in the methane-containing gas.

[0049] According to an embodiment of the present invention, the carbon dioxide-containing gas is selected from fresh carbon dioxide-rich gas, or a mixture of fresh carbon dioxide-rich gas and recycled carbon dioxide.

[0050] Preferably, the recovered carbon dioxide comes from the carbon dioxide gas obtained from the above-mentioned decarbonization process.

[0051] According to an embodiment of the present invention, when the carbon dioxide-containing gas is selected from fresh carbon dioxide-rich gas, the molar ratio of the carbon dioxide to the total hydrocarbon carbon number is 0.1 to 4.0, preferably the molar ratio of the carbon dioxide to the total hydrocarbon carbon number is 0.9 to 3.6, and further, the molar ratio of the carbon dioxide to the total hydrocarbon carbon number is 2.5 to 3.0.

[0052] According to an embodiment of the present invention, when the carbon dioxide-containing gas is selected from a mixture of fresh carbon dioxide-rich gas and recycled carbon dioxide, the molar ratio of the carbon dioxide to the total hydrocarbon carbon number is 0.1 to 5.5, preferably the molar ratio of the carbon dioxide to the total hydrocarbon carbon number is 0.3 to 4, and further, the molar ratio of the carbon dioxide to the total hydrocarbon carbon number is 0.6 to 3.

[0053] According to an embodiment of the present invention, the fresh carbon dioxide-rich gas is selected from gases with a carbon dioxide molar ratio greater than 95%, preferably the fresh carbon dioxide-rich gas is selected from gases with a carbon dioxide molar ratio greater than 99%.

[0054] Preferably, the fresh carbon dioxide-rich gas further includes at least one of hydrogen, carbon monoxide and nitrogen.

[0055] As an example, the fresh carbon dioxide-rich gas includes 99.171% CO 2 , 0.416% H 2 , 0.018% CO molar composition, and 0.395% N 2 in molar ratio.

[0056] According to an embodiment of the present invention, the methane-containing gas is selected from one, two or more of natural gas, shale gas, coalbed methane, coke oven gas, waste gas, biogas and refinery gas, for example, coke oven gas, natural gas or biogas.

[0057] As an example, in molar ratio, the natural gas comprises 98.4% CH4, 0.02% H2, 0.314% N2, 0.86% C2H6, 0.27% C3H8, 0.05% O2, 0.08% C4H8 and 0.006% C5H 12 .

[0058] As another example, in molar ratios, the biogas includes 60.1% CH4, 0.5% H2, 37.4% CO2, 1.2% N2, 0.3% O2, and 0.5% H2S.

[0059] As another example, in molar ratios, the coke oven gas includes 23.8% CH4, 59.2% H2, 3% CO2, 6.5% CO, 4.5% N2, 2.5% C2H6, 0.5% O2, and 0.028% H2S.

[0060] According to an embodiment of the present invention, in step 1), the raw gas is purified, including making the total sulfur content of the raw gas less than 1.0 ppm, and further making the total sulfur content of the raw gas less than 0.6 ppm.

[0061] As an example, in step 1), the raw gas is purified, which includes the following steps: firstly desulfurizing the methane-containing gas, then mixing it with the carbon dioxide-containing gas and desulfurizing it again.

[0062] As another example, in step 1), the raw gas is purified, which includes the following steps: mixing the methane-containing gas and the carbon dioxide-containing gas and desulfurizing them.

[0063] According to an embodiment of the present invention, before step 2), the following step is further included: preheating the mixed gas to 450-650°C, preferably, preheating the mixed gas to 500-600°C, such as 550°C, 600°C, or 640°C.

[0064] According to an embodiment of the present invention, the pressure of the purge gas reaction in step 2) is 0-3.0 MPaG, preferably 0.3-2.0 MPaG, for example 0.4 MPaG, 1.1 MPaG, or 1.8 MPaG.

[0065] According to an embodiment of the present invention, the temperature of the purified gas reaction in step 2) is 500-1100°C, preferably 550-950°C, for example 860°C, 900°C, or 960°C.

[0066] According to an embodiment of the present invention, the space velocity of the purified gas reaction in step 2) is 1000 to 10000 h -1 The space velocity of the purified gas reaction is preferably 2000 to 8000 h -1 , for example 3000h -1 、 5400h -1 , 7900h -1 .

[0067] According to an embodiment of the present invention, the purified gas reaction in step 2) is carried out under catalyst conditions, and the catalyst has the definition as described above.

[0068] According to an embodiment of the present invention, the carbon monoxide purification in step 3) can be carried out by methods known in the art, such as pressure swing adsorption, membrane separation, etc.

[0069] According to an embodiment of the present invention, step 3) further includes the following step: passing the remaining gas after carbon monoxide purification into the heating unit of the dry reforming module as fuel gas.

[0070] As an example, the recovered carbon dioxide gas is mixed with fresh carbon dioxide-rich gas in a pretreatment module, and then the methane-containing gas is introduced into the pretreatment module for mixing. After pretreatment, it is introduced into a dry reforming module for reaction. The reaction gas is first subjected to carbon dioxide recovery and introduced into the pretreatment module, and then carbon monoxide is purified.

[0071] As another example, fresh carbon dioxide-rich gas and methane-containing gas are introduced into a pretreatment module for mixing, and after pretreatment, introduced into a dry reforming module for reaction, and the reaction gas is purified for carbon monoxide.

[0072] Beneficial effects

[0073] (1) The present invention adopts dry reforming of carbon dioxide and methane to prepare carbon monoxide. No water vapor is added during the reaction process, and only carbon dioxide is used as a conversion agent. This not only saves energy and reduces consumption and emissions, but also realizes resource utilization of carbon dioxide by net consuming greenhouse gas carbon dioxide.

[0074] (2) The present invention recovers CO2 first and then separates carbon monoxide. The cost of CO2 is used to determine whether to recover carbon dioxide in the reaction gas. When the cost of CO2 is high, carbon dioxide can be recovered to reduce production costs. When the cost of CO2 is low, carbon dioxide can be not recovered to reduce recovery costs. The two methods are used in combination to effectively control the preparation cost. At the same time, the intake concentration of CO2 can be adjusted according to the concentration of CH4 and H2 in the raw gas, and the ratio of CO2, CH4 and H2 can be controlled within an appropriate range to accelerate the reaction speed. The remaining gas after carbon separation also contains combustible gases such as H2 and methane, which are introduced into the heating unit as fuel for combustion and heat release. The present invention separates CO2 from the remaining gas containing combustible gases such as H2 and methane, reuses CO2 as a reaction gas, and uses the remaining gas as fuel. Compared with the prior art in which gases such as CO2, H2, and methane are recovered and mixed into the raw gas, resulting in an uncontrollable ratio of CO2 to H2 and CH4 in the reactor, the present invention effectively utilizes the waste gas after the reaction while ensuring the rapid progress of the reaction and effectively improving the reaction efficiency.

[0075] (3) The present invention carries out the reaction in a one-step process, uses a catalyst, and sets the current reaction conditions to the optimal conditions to achieve the effect of efficiently preparing CO2. Compared with the prior art, the reaction is carried out in multiple stages and requires the use of multiple catalysts. Due to the different optimal conditions of different reactions and catalysts, the preparation efficiency is relatively low. The present invention simplifies the process, not only reducing production costs but also improving preparation efficiency.

[0076] (4) The present invention uses methane-containing gas as raw gas and fuel gas, and inputs them into the raw gas pretreatment module and the dry reforming module through the same pipeline. Compared with the existing dry reforming reaction in which the raw gas and fuel gas are the same or different and are transported through different pipelines, it can effectively reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 This is a flow chart of a method for preparing carbon monoxide using recycled carbon dioxide as a raw material in Example 1 of the present invention;

[0078] Figure 2 This is a flow chart of a method for preparing carbon monoxide using fresh carbon dioxide as a raw material in Example 2 of the present invention. DETAILED DESCRIPTION

[0079] The structure and preparation method of the present invention will be further described in detail below with reference to specific examples. It should be understood that the following examples are merely exemplary illustrations and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection intended by the present invention.

[0080] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0081] System Example:

[0082] See also Figure 1 and Figure 2 As shown, a system for preparing carbon monoxide by dry reforming carbon dioxide and methane-containing gas includes a raw gas pretreatment module, a dry reforming module and a carbon monoxide purification module connected in sequence, wherein a carbon dioxide recovery unit can also be provided between the dry reforming module and the carbon monoxide purification module.

[0083] The raw gas pretreatment module is connected to an external gas source (the raw gas includes methane-containing gas and carbon dioxide-rich gas, and the gas source includes a methane-containing gas pipeline and a carbon dioxide-rich gas pipeline), introduces the raw gas and mixes and purifies the raw gas. The raw gas pretreatment module includes a mixing unit and several purification units. The mixing unit is used to mix different raw gases, and the purification unit is used to remove impurities in the raw gas.

[0084] The purification unit includes a combination of one or more of a deoiling unit, a naphthalene removal unit, a crude desulfurization unit, a fine desulfurization unit, a dehydration unit, and a pre-reforming unit. When there are multiple purification units, different purification units are connected in sequence, and the connection order is arranged according to actual needs. For example, the purification unit includes a crude desulfurization unit and a fine desulfurization unit. The crude desulfurization unit is arranged at the feed port of the methane-containing gas and is used to remove inorganic sulfur in the methane-containing gas. The fine desulfurization unit is connected to the mixing unit and is used to perform fine desulfurization on the mixed gas.

[0085] The dry reforming module is used to provide an environment for dry reforming reaction for the purified raw gas. The dry reforming module includes a reaction unit and a heating unit. The reaction unit is used to carry out dry reforming reaction, and the heating unit is used to burn fuel (the heating unit is used to burn methane-containing gas and / or carbon monoxide purified residual gas) to provide the reaction unit with the temperature required for the reaction. The fuel includes methane-containing gas from the same source as the raw gas; the dry reforming module can be a dry reforming converter commonly used in the art, such as a tubular furnace reactor for natural gas steam reforming.

[0086] The dry reforming module is also provided with a temperature adjustment unit, a pressure adjustment unit and an air velocity adjustment unit; the temperature adjustment unit is used to adjust the reaction temperature in the dry reforming module, the pressure adjustment unit is used to adjust the reaction pressure in the dry reforming module, and the air velocity adjustment unit is used to adjust the air velocity in the dry reforming module.

[0087] The carbon monoxide purification module is used to purify carbon monoxide from the gas generated by the reaction in the dry reforming module, and is also used to introduce the remaining gas after carbon monoxide purification (hereinafter referred to as carbon monoxide purified residual gas) into the dry reforming module as fuel gas.

[0088] In this embodiment, the methane-containing gas in the heating unit and the methane-containing gas in the raw gas are transported through the same gas pipeline, that is, the heating unit and the raw gas pretreatment module share a set of methane-containing gas transportation pipelines. Compared with the existing dry reforming reaction in which the raw gas and the fuel gas are the same or different and are transported through different pipelines, this can effectively reduce costs.

[0089] A catalyst is provided in the dry reforming module. The catalyst is used to catalyze the reaction of methane and carbon dioxide. The catalyst is a Ni-based catalyst. The carrier of the catalyst is selected from a composite oxide carrier. The catalyst may also include an additive.

[0090] A preheating unit is further provided between the dry reforming module and the raw gas pretreatment module. The preheating unit is used to preheat the gas pretreated by the raw gas pretreatment module. The preheating unit is, for example, a heat exchanger.

[0091] A pressure regulating unit is further provided between the raw gas pretreatment module and the preheating unit, and the pressure regulating unit is used to adjust the pressure of the mixed gas; for example, the pressure regulating unit is a compressor.

[0092] A heat recovery unit is also provided between the dry reforming module and the carbon monoxide purification module, and the heat recovery unit is used to recover heat from the gas generated by the reaction in the dry reforming module.

[0093] A steam-water separation unit is provided between the heat recovery unit and the carbon monoxide purification module. The steam-water separation unit is used to remove moisture from the gas generated by the reaction. The steam-water separation unit is, for example, a gas-liquid separation tank.

[0094] A carbon dioxide recovery unit is also provided between the steam-water separation unit and the carbon monoxide purification module. The carbon dioxide recovery unit is used to recover carbon dioxide in the gas produced by the reaction. The carbon dioxide recovery unit is connected to the raw gas pretreatment module and is used to introduce high-concentration carbon dioxide into the raw gas pretreatment module as carbon dioxide-rich gas.

[0095] An embodiment of a method for preparing carbon monoxide using the above system:

[0096] Example 1

[0097] S1, industrial natural gas (CH4 molar composition 98.4%, H2 molar composition 0.02%, N2 molar composition 0.314%, C2H6 molar composition 0.86%, C3H8 molar composition 0.27%, O2 molar composition 0.05%, C4H8 molar composition 0.08%, C5 ... 12 The molar composition is 0.006%) and is divided into two parts: the flow rate is 336Nm 3 / h of natural gas enters the dry reforming module as fuel gas, with a flow rate of 2241Nm 3 / h of natural gas enters the raw gas pretreatment module as raw material.

[0098] S2, configured flow rate is 3810Nm 3 / h of fresh carbon dioxide-rich gas (CO2 molar composition 99.171%, H2 molar composition 0.416%, CO molar composition 0.018%, N2 molar composition 0.395%).

[0099] S3, the carbon dioxide recovered from the carbon dioxide recovery unit is discharged at a flow rate of 24451Nm 3 / h is first mixed with fresh carbon dioxide-rich gas and then mixed with natural gas, so that the molar ratio of carbon dioxide to total hydrocarbon carbon number in the mixed gas is 1.66. The mixed gas is pressurized to 1.6MPaG by a compressor and enters the fine desulfurization module for desulfurization and purification, so that the total sulfur content of the raw material is less than 1.0ppm.

[0100] S4: The purified gas is sent to the dry reforming converter flue gas preheating system to be preheated to 640°C. The preheated purified gas directly enters the dry reforming converter for reaction. The reaction pressure is 1.1 MPaG, the reaction temperature is 900°C, and the space velocity is 3000h -1 The catalyst used is a Ni-based catalyst, supported by a composite oxide of MgO and γ-Al2O3 in a molar ratio of 1:1; the Ni content is 15%. Precious metals or rare earth metals can be used as additives for modification according to different reaction requirements.

[0101] S5, the gas flow rate at the outlet of the converter is 11404Nm 3 / h (dry basis: H2 molar composition 25.32%, CO2 molar composition 21.84%, CO molar composition 52.16%, CH4 molar composition 0.49%, N2 molar composition 0.19%), after heat recovery and cooling, enters the gas-liquid separation tank for water separation. After water removal, the gas is introduced into the carbon dioxide recovery unit for decarbonization treatment in the carbon dioxide recovery unit. The decarbonization adopts the MDEA decarbonization process (alcoholamine desulfurization and decarbonization process), and all the removed carbon dioxide is returned to step S3 for recycling.

[0102] S6, the gas after decarbonization treatment enters the carbon monoxide purification module. The carbon monoxide purification adopts the pressure swing adsorption process, and the carbon monoxide yield obtained is 90%, and 5354Nm of carbon monoxide can be obtained. 3 / h, while the net consumption of carbon dioxide is 5384kg / h. The remaining gas after purification returns to the dry reforming module and is mixed with the fuel gas as the dry reforming converter fuel; the fuel consumed in the preparation process of this embodiment is as follows: 336Nm 3 / h, electricity 957kWh, primary water 9.236t / h, and the comprehensive energy consumption per unit product is 0.0995kgce / Nm 3 .

[0103] Example 2

[0104] S1, the biogas from the pipe network (CH4 molar composition 60.1%, H2 molar composition 0.5%, CO2 molar composition 37.4%, N2 molar composition 1.2%, O2 molar composition 0.3%, H2S molar composition 0.5%) is divided into two parts, of which 661Nm 3 / h biogas enters the dry reforming module as fuel gas, 2241Nm 3 / h of biogas enters the raw gas pretreatment module as raw material.

[0105] S2, the raw biogas is introduced into the desulfurization module to remove most of the inorganic sulfur, and then directly mixed with the flow rate of 2891Nm 3 / h of carbon dioxide-rich gas (CO2 molar composition 99.171%, H2 molar composition 0.416%, CO molar composition 0.018%, N2 molar composition 0.395%) is mixed to make the molar ratio of carbon dioxide to total hydrocarbon carbon number 2.74 to obtain a mixed raw gas.

[0106] S3: The mixed raw gas is pressurized to 2.2 MPaG by the compressor and enters the fine desulfurization module for desulfurization and purification, so that the total sulfur content of the raw material is less than 1.0 ppm. The purified gas is sent to the flue gas preheating system of the dry reforming converter to be preheated to 550°C. After preheating, the raw gas directly enters the dry reforming converter for reaction at a reaction pressure of 1.8 MPaG, a reaction temperature of 960°C, and a space velocity of 5400 h -1 In the above reaction process, the catalyst used in the present invention is a Ni-based catalyst. The carrier is a composite oxide carrier with a molar ratio of MgO to γ-Al2O3 of 0.5:1, preferably 1:1; the Ni content is 10%. Precious metals or rare earth metals can be used as additives for modification according to different reaction requirements. The gas at the outlet of the converter is 6804Nm 3 / h (dry basis: H2 molar composition 25.01%, CO2 molar composition 20.75%, CO molar composition 53.32%, CH4 molar composition 0.35%, N2 molar composition 0.57%), after heat recovery and cooling, it enters the gas-liquid separation tank for water separation, and after water removal, the gas enters the carbon monoxide purification module.

[0107] S4. Carbon monoxide purification uses pressure swing adsorption process. When the carbon monoxide yield in this embodiment is 90%, 3265Nm of carbon monoxide can be obtained. 3 / h, while consuming 2480kg / h of carbon dioxide. The remaining gas after purification is returned to the dry reforming module and mixed with the fuel gas as fuel for the dry reforming converter. The total fuel consumption in the process is 661Nm 3 / h, electricity 589.3kWh, primary water 7.736t / h, and the comprehensive energy consumption per unit product is 0.1726kgce / Nm 3 .

[0108] Example 3

[0109] S1. Coke oven gas from a chemical plant (CH4 molar composition 23.8%, H2 molar composition 59.2%, CO2 molar composition 3%, CO molar composition 6.5%, N2 molar composition 4.5%, C2H6 molar composition 2.5%, O2 molar composition 0.5%, H2S molar composition 0.028%) is divided into two parts, with a flow rate of 486Nm 3 / h of coke oven gas enters the dry reforming module as fuel gas with a flow rate of 2241Nm 3 / h of coke oven gas enters the raw gas pretreatment module as raw material.

[0110] S2, pressurize the raw coke oven gas to 0.15MPaG and then enter the deoiling, denaphthalene and crude desulfurization modules to remove tar, naphthalene and most of the inorganic sulfur. 3 / h fresh carbon dioxide-rich gas (CO2 molar composition 99.171%, H2 molar composition 0.416%, CO molar composition 0.018%, N2 molar composition 0.395%).

[0111] S3, the carbon dioxide recovered from the carbon dioxide recovery unit 3149Nm 3 / h, first mixed with fresh carbon dioxide-rich gas, and then mixed with coke oven gas, controlling the molar ratio of carbon dioxide to total hydrocarbon carbon number to be 3.2. The mixed gas is pressurized to 1.0 MPaG by a compressor and then sent to the fine desulfurization module to remove a small amount of organic sulfur and hydrogen sulfide, so that the total sulfur content of the raw material is less than 1.0 ppm to obtain purified gas.

[0112] S4: The purified gas is sent to the dry reforming converter flue gas preheating system to be preheated to 600°C. After preheating, the raw gas directly enters the dry reforming converter for reaction. The reaction pressure is 0.4MPaG, the reaction temperature is 860°C, and the space velocity is 7900h -1 In the above reaction process, the catalyst used in the present invention is a nickel-based catalyst. The support is a composite oxide support with a molar ratio of MgO to γ-Al2O3 of 2:1; the nickel content is 12%. Precious metals or rare earth metals can be used as additives for modification according to different reaction requirements.

[0113] S5, the outlet gas of the converter is set at a flow rate of 7206Nm 3 / h (dry basis: H2 molar composition 15.74%, CO2 molar composition 43.67%, CO molar composition 39.07%, CH4 molar composition 0.02%, N2 molar composition 1.5%). After heat recovery and cooling, it enters the gas-liquid separation tank for water separation. After water removal, the gas enters the carbon dioxide recovery unit. Decarbonization uses a pressure swing adsorption process. All removed carbon dioxide is returned to S3 for recycling, and the remaining gas enters the carbon monoxide purification module. Carbon monoxide purification uses a membrane separation process.

[0114] When the carbon monoxide yield is 90%, 2552 Nm of carbon monoxide can be obtained. 3 / h, while the net consumption of carbon dioxide is 3091kg / h. The remaining gas after purification returns to the dry reforming module and is mixed with the fuel gas as the fuel for the dry reforming converter; the total fuel consumption in the process is 486Nm 3 / h, electricity 604.4kWh, primary water 7.486t / h, unit product comprehensive energy consumption is 0.1423kgce / Nm 3 .

[0115] Comparative Example 1 (using Example 1 in CN102838116A as a comparative example)

[0116] The coke oven gas from chemical products (CH4 molar composition 26.87%, H2 molar composition 56.92%, CO2 molar composition 2.92%, CO molar composition 7.13%, N2 molar composition 2.93%, C2H6 molar composition 2.63%, O2 molar composition 0.6%, H2S molar composition 0.028%) is divided into two parts, with a flow rate of 2263Nm 3 / h of coke oven gas enters the reaction unit as fuel gas with a flow rate of 2241Nm 3 / h of coke oven gas enters the raw gas pretreatment module as raw material.

[0117] The raw coke oven gas is pressurized to 0.15MPaG and then enters the de-oiling, de-naphthalene and crude desulfurization modules to remove tar, naphthalene and most of the inorganic sulfur. 3 / h fresh carbon dioxide-rich gas (CO2 molar composition 93%, N2 molar composition 7%), and the molar ratio of carbon dioxide to raw coke oven gas is controlled at 2.2.

[0118] The gas circulated back to the system is 10270Nm 3 / h (dry basis: H2 molar composition 9.57%, CO2 molar composition 83.34%, CH4 molar composition 2.99%, N2 molar composition 3.98%, O2 molar composition 0.12%) is first mixed with fresh carbon dioxide-rich gas, and then mixed with coke oven gas, and then sent to the fine desulfurization module after being pressurized to 1.0MPaG by the compressor to remove a small amount of organic sulfur and hydrogen sulfide, so that the total sulfur content of the raw material is less than 0.1ppm.

[0119] The purified gas is preheated to 600°C and enters the reactor for a three-stage reaction:

[0120] In the first reaction section, part of the methane and part of the hydrogen in the mixed gas undergo a non-catalytic conversion reaction with carbon dioxide; in the second reaction section, under the action of the bifunctional catalyst Ni-Fe-Cu / CaO / Al2O3, the methane in the reaction gas after the first reaction section undergoes a catalytic reforming reaction with carbon dioxide to produce carbon monoxide and hydrogen, and the hydrogen and carbon dioxide undergo a pseudo-water-gas shift reaction to produce carbon monoxide and water vapor; in the third reaction section, under the action of the reverse shift catalyst Fe-Cu / CaO / Al2O3, the hydrogen and carbon dioxide in the reaction gas after the second reaction undergo a reverse shift reaction to produce a reformed gas mainly containing carbon monoxide.

[0121] The reaction temperature in the reactor is 700-1300°C, the reaction pressure is 0.4 MPaG, and the space velocity is 3500-8500 h -1 The outlet gas after reaction is 14528Nm 3 / h (dry basis: H2 molar composition 6.81%, CO2 molar composition 58.93%, CO molar composition 29.22%, CH4 molar composition 2.12%, N2 molar composition 2.83%, O2 molar composition 0.09%) after heat recovery and cooling, enters the gas-liquid separation tank for water separation, and after water removal, the gas enters the carbon monoxide purification module. The carbon monoxide obtained is 4258Nm 3 / h, the remaining gas after purification is recycled, and the total fuel consumption in the process is 2241Nm 3 / h, electricity 1500.2kWh, primary water 13.125t / h, unit product comprehensive energy consumption is 0.3732kgce / Nm 3 .

[0122] It can be seen that the present invention uses the same reaction system to produce carbon monoxide from a variety of raw materials, and the fuel consumption during the preparation process is 330-661Nm 3 / h, electricity consumption is 580-960kWh, primary water consumption is 7.5-9.3t / h, and the comprehensive energy consumption per unit product is 0.01-0.15kgce / Nm 3 , which is far lower than the energy consumption in the prior art, that is, the present invention can achieve the technical effect of energy saving and emission reduction.

[0123] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for preparing carbon monoxide, characterized in that: The following steps are involved: 1) mixing methane-containing gas and carbon dioxide-containing gas, purifying the mixed gas to obtain purified gas, and preheating the purified gas to 450-650° C.; 2) Add the purified gas to the dry reforming module for reaction. The pressure of the purified gas reaction is 0-3.0 MPa, the temperature of the purified gas reaction is 500-1100°C, and the space velocity of the purified gas reaction is 1000-10000h -1 , obtaining a reaction gas; 3) Separating carbon monoxide from the reaction gas; The methane-containing gas is selected from one, two or more of natural gas, shale gas, coalbed methane, coke oven gas, raw coal gas, biogas and refinery gas; the carbon dioxide-containing gas is selected from fresh carbon dioxide-rich gas, or a mixture of fresh carbon dioxide-rich gas and recycled carbon dioxide; When the carbon dioxide-containing gas is selected from fresh carbon dioxide-rich gas, the molar ratio of carbon dioxide to total hydrocarbon carbon number is 0.1 to 4.0, and the fresh carbon dioxide-rich gas is selected from a gas having a carbon dioxide molar ratio greater than 95%; When the carbon dioxide-containing gas is selected from a mixture of fresh carbon dioxide-rich gas and recycled carbon dioxide, the molar ratio of carbon dioxide to total hydrocarbon carbon number is 0.1 to 5.5; The method is carried out in a system for preparing carbon monoxide, the system comprising a raw gas pretreatment module, a dry reforming module and a carbon monoxide purification module connected in sequence, wherein the raw gas comprises methane-containing gas and carbon dioxide-containing gas; The raw gas pretreatment module includes a mixing unit and a purification unit, wherein the mixing unit is used to mix the raw gas to obtain a mixed gas, and the purification unit is used to purify the mixed gas; The dry reforming module is used to provide a dry reforming reaction environment for the purified mixed gas, and the dry reforming module includes a reaction unit and a heating unit. The reaction unit is used to perform the dry reforming reaction, and the heating unit is used to perform fuel combustion to provide the reaction unit with the temperature required for the reaction. The fuel includes methane-containing gas from the same source as the feed gas; The carbon monoxide purification module is used to purify carbon monoxide from the gas generated by the reaction in the dry reforming module.

2. The method for preparing carbon monoxide according to claim 1, wherein Step 1) further comprises the following step: adding methane-containing gas as fuel into the heating unit of the dry reforming module for combustion to provide the temperature required for the reaction.

3. The method for preparing carbon monoxide according to claim 1, wherein After step 3), the following step is also included: the remaining gas after carbon monoxide purification is introduced into the heating unit of the dry reforming module as fuel gas.

4. The method for preparing carbon monoxide according to claim 1, wherein After step 2) and before step 3), the method further comprises the following step: removing carbon dioxide gas from the reaction gas to obtain recovered carbon dioxide.

5. The method for preparing carbon monoxide according to claim 1, wherein After step 2), the method further includes the following steps: introducing the recovered carbon dioxide gas as carbon dioxide-containing gas into a raw gas pretreatment module.

6. The method for preparing carbon monoxide according to any one of claims 1 to 5, characterized in that: The methane-containing gas is coke oven gas, natural gas or biogas.

7. The method for preparing carbon monoxide according to any one of claims 1 to 5, characterized in that: In step 1), the raw gas is purified, including making the total sulfur content of the raw gas less than 1.0 ppm.

8. The method for preparing carbon monoxide according to any one of claims 1 to 5, characterized in that: The heating unit is used to burn the methane-containing gas and / or carbon monoxide purified residual gas; The dry reforming module is provided with a catalyst, which is a Ni-based catalyst. The carrier of the catalyst is selected from a composite oxide carrier. The Ni content in the Ni-based catalyst is 10-15%, and the composite oxide carrier includes MgO and γ-Al2O3.

9. The method for preparing carbon monoxide according to claim 8, characterized in that The molar ratio of MgO to γ-Al2O3 is (0.5-2):1; The catalyst also includes a promoter, which includes precious metals and / or rare earth metals. The precious metal includes at least one of gold, silver, and platinum, and the rare earth metal includes at least one of scandium, yttrium, lanthanum, cerium, praseodymium, and neodymium.

10. The method for preparing carbon monoxide according to any one of claims 1 to 5, characterized in that: A heat recovery unit is also provided between the dry reforming module and the carbon monoxide purification module. The heat recovery unit is used to recover heat from the gas generated by the reaction in the dry reforming module. A steam-water separation unit is provided between the heat recovery unit and the carbon monoxide purification module. A carbon dioxide recovery unit is also provided between the steam-water separation unit and the carbon monoxide purification module. The carbon dioxide recovery unit is used to recover carbon dioxide from the gas generated by the reaction.

11. The method for preparing carbon monoxide according to any one of claims 1 to 5, characterized in that: The carbon dioxide recovery unit is connected to the raw gas pretreatment module; the carbon monoxide purification module is also used to introduce the remaining gas after carbon monoxide purification into the dry reforming module as fuel.

12. The method for preparing carbon monoxide according to any one of claims 1 to 5, characterized in that: The purification unit includes a combination of one or more of a deoiling unit, a naphthalene removal unit, a rough desulfurization unit, a fine desulfurization unit, a dehydration unit, and a pre-reforming unit.

13. The method for preparing carbon monoxide according to any one of claims 1 to 5, characterized in that: When there are multiple purification units, different purification units are connected in sequence, and the connection order is arranged according to actual needs.

Images