Method and system for producing methanol

Abstract

The present invention relates to the field of industrial methanol production, and discloses a method and system for producing methanol. The method comprises: first contacting a hydrocarbon-containing stream with water to obtain a recombined synthetic gas; dividing the recombined synthetic gas into A gas and B gas, and in the presence of a reverse water vapor shift catalyst, second contacting the A gas with carbon dioxide to obtain a reverse water vapor shift synthetic gas; mixing the B gas with the reverse water vapor shift synthetic gas to obtain a synthetic gas raw material; and subjecting the synthetic gas raw material to a methanol synthesis reaction to obtain a synthetic product containing methanol. The method and system for producing methanol provided by the present invention can utilize excess H2 in the recombined synthetic gas, increase the content of CO in the synthetic gas raw material, realize the increase of methanol production in the process of producing methanol from coke oven gas, increase enterprise benefits, effectively consume CO2, and realize the resource utilization of CO2.

Description

Technical Field

[0001] The present invention relates to the field of industrial methanol production, and in particular to a method and system for producing methanol. Background Art

[0002] Since the Industrial Revolution, the amount of carbon dioxide emitted into the atmosphere has increased year by year, and the greenhouse effect of the atmosphere has also increased, causing a series of serious problems such as global warming. Therefore, how to realize the resource utilization of CO2 has attracted widespread attention in the chemical industry. The most direct way to realize the resource utilization of CO2 is to react CO2 with H2 to produce chemicals or oil products. The CO2+H2 reaction is conceptually sound, but it is very difficult to achieve technically. Even if it is achieved, its economic efficiency is difficult to guarantee. From a thermodynamic analysis, CO2 is the most stable end product of carbon combustion and is difficult to activate directly. Taking methanol synthesis as an example, the reaction of CO2 and H2 to produce methanol is equivalent to the combination of CO2+H2=CO+H2O (reverse water vapor shift) and CO+2H2=CH3OH. However, the two reactions are opposite in thermodynamics. The former is endothermic and requires a high temperature reaction of more than 500℃; the latter is exothermic and requires a low temperature reaction of less than 300℃. The two cannot be unified, which results in an impact on the reaction efficiency. The single-pass conversion rate of CO2 hydrogenation to produce methanol is about 20%, which affects the process economy.

[0003] Coke oven gas is a by-product of coking. The raw gas from the carbonization chamber of the coke oven is called coke oven gas after a series of purification treatments and recovery of chemicals such as benzene and naphthalene. Its composition (vol%) is mainly H2 (54-59), CH4 (24-28), CO (5.5-7), CO2 (1-3) and N2 (3-5), as well as H2S (0.02-0.2g / m 3 ). A large amount of coke oven gas is produced in the process of refining coal into coke. Making full use of the coke oven gas produced in the coking process can not only reduce the pollution caused by coke oven gas to the environment, but also achieve the purpose of saving energy. Coke oven gas is rich in methane and hydrogen, so it can be used as both a fuel and a chemical raw material. In the process of making methanol from coke oven gas, the coke oven gas is rich in H2, and the H2 content is even higher after reforming, so it is surplus for making chemicals. Taking the existing coke oven gas to methanol process as an example, the process is that after the coke oven gas is purified (removing tar, benzene, and naphthalene), the inorganic sulfur and organic sulfur in the raw gas are removed through wet desulfurization, hydrodesulfurization and other processes, and then the methane and low-carbon alkanes in the hydrocarbon-containing stream are converted into synthesis gas through reforming (steam reforming and / or autothermal reforming). The H2 content in the reformed synthesis gas is excessive, and n(H2-CO2) / (CO+CO2) is close to 3, which is much higher than the gas modulus n(H2-CO2) / n(CO+CO2)=2 required for producing methanol from synthesis gas. The excess H2 does not participate in the reaction, so the excess H2 is wasted.

[0004] Therefore, developing a suitable process for producing methanol by adding carbon dioxide to coke oven gas to better realize the resource utilization of CO2 and the utilization of excess H2 is of great significance for energy conservation and emission reduction, environmental protection, and the improvement of economic and social benefits. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem of excess H2 in the coke oven gas to methanol process in the prior art, and to provide a method and system for producing methanol to increase the CO content in the synthesis gas raw material, maximize the use of excess H2, consume CO2 at the same time to achieve resource utilization of CO2, and increase the output of methanol.

[0006] In order to achieve the above object, the present invention provides a method for producing methanol in a first aspect, the method comprising the following steps:

[0007] (1) contacting a hydrocarbon-containing stream with water to obtain a reformed synthetic gas;

[0008] (2) dividing the reformed synthesis gas into a gas A and a gas B, and subjecting the gas A to a second contact with carbon dioxide in the presence of a reverse water gas shift catalyst to obtain a reverse water gas shift synthesis gas;

[0009] (3) Mixing the B gas with the reverse water gas shift synthesis gas to obtain a synthesis gas feedstock; and subjecting the synthesis gas feedstock to a methanol synthesis reaction to obtain a synthetic product containing methanol.

[0010] A second aspect of the present invention provides a system for producing methanol, which includes a reforming reaction unit, a reverse water gas shift reaction unit, an optional synthesis gas mixing unit and a methanol synthesis reaction unit connected in sequence.

[0011] Through the above technical scheme, the method and system for producing methanol provided by the present invention can utilize the excess H2 in the reformed syngas, increase the CO content in the syngas raw material, achieve an increase in methanol production in the process of producing methanol from coke oven gas, increase corporate benefits, effectively consume CO2, and realize the resource utilization of CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic diagram of a method and system for producing methanol according to an embodiment of the present invention;

[0013] Figure 2 It is a schematic diagram of a method and system for producing methanol according to a preferred embodiment of the present invention;

[0014] Figure 3 It is a schematic diagram of a method and system for producing methanol according to another preferred embodiment of the present invention;

[0015] Figure 4It is a schematic diagram of a method and system for producing methanol according to another preferred embodiment of the present invention;

[0016] Figure 5 It is a schematic diagram of a method and system for producing methanol according to another preferred embodiment of the present invention;

[0017] Figure 6 It is a process flow chart of producing methanol from coke oven gas in the prior art;

[0018] Description of Reference Numerals

[0019] Ⅰ. Pretreatment unit Ⅱ. Reforming reaction unit Ⅲ. Reverse water-steam shift reaction unit

[0020] Ⅳ、Heat exchange unit Ⅴ、Synthesis gas mixing unit Ⅵ、Separation unit

[0021] VII. Methanol synthesis reaction unit VIII. Distillation unit

[0022] 1. Hydrocarbon-containing raw materials 2. Hydrocarbon-containing logistics 3. A-share gas

[0023] 4. B gas 5. First gas flow 6. Second gas flow

[0024] 7. Carbon dioxide after heat exchange 8. First airflow after heat exchange 9. Synthesis gas raw material

[0025] 10. Separation of water 11. Raw materials 12. Synthetic products containing methanol

[0026] 13. Methanol products 14. Carbon dioxide 15. Water

[0027] 16. Recombination synthesis gas 17. Reverse water vapor shift synthesis gas DETAILED DESCRIPTION

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] A first aspect of the present invention provides a method for producing methanol, the method comprising the steps of:

[0030] (1) contacting a hydrocarbon-containing stream with water to obtain a reformed synthetic gas;

[0031] (2) dividing the reformed synthesis gas into a gas A and a gas B, and subjecting the gas A to a second contact with carbon dioxide in the presence of a reverse water gas shift catalyst to obtain a reverse water gas shift synthesis gas;

[0032] (3) Mixing the B gas with the reverse water gas shift synthesis gas to obtain a synthesis gas feedstock; and subjecting the synthesis gas feedstock to a methanol synthesis reaction to obtain a synthetic product containing methanol.

[0033] The inventors of the present invention found in the course of research that in the preparation process of methanol, the reaction of CO2 and H2 to produce methanol is equivalent to the combination of CO2+H2=CO+H2O (reverse water vapor shift) and CO+2H2=CH3OH. However, the two reactions are opposite in thermodynamics. The former is endothermic and requires a high temperature reaction above 500°C; while the latter is exothermic and requires a low temperature reaction below 300°C. The two cannot be unified, which results in affecting the reaction efficiency. The single-pass conversion rate of CO2 hydrogenation to produce methanol is only about 20%, which affects the economy of the process. If the reverse water vapor shift process (CO2+H2=CO+H2O) is listed separately, and then the synthesis gas to produce methanol reaction (CO+2H2=CH3OH) is carried out, the contradiction of the two reactions in thermodynamics can be resolved, the reaction efficiency can be improved, and thus the methanol output can be increased.

[0034] According to some embodiments of the present invention, in step (1), the hydrocarbon-containing stream is first contacted with water to obtain a reformed synthetic gas. Preferably, the hydrocarbon-containing stream contains methane and / or hydrocarbons with a carbon number of not less than 2; wherein the hydrocarbons with a carbon number of not less than 2 are generally of the formula C x H y , wherein x≥2, y≥4; more preferably, the hydrocarbon-containing stream contains methane and / or low-carbon alkanes having a carbon number of 2-5; further preferably, the hydrocarbon-containing stream also contains at least one of water (water vapor), carbon monoxide, carbon dioxide, hydrogen, nitrogen and argon; further preferably, the mass content of sulfur in the hydrocarbon-containing stream is less than 200 ppm.

[0035] According to some embodiments of the present invention, preferably, the reaction occurring in the first contacting comprises a steam reforming reaction and / or an autothermal reforming reaction. For methane, the steam reforming reaction comprises:

[0036] CH4+H2O=CO+3H2 (i)

[0037] CH4+2H2O=CO2+4H2 (ii)

[0038] For hydrocarbons with a carbon number of not less than 2, the steam reforming reaction includes:

[0039] C x H y +xH2O=xCO+(x+y / 2)H2 (iii)

[0040] Typically, the steam reforming reaction is accompanied by a water-gas shift reaction:

[0041] CO+H2O=CO2+H2 (iv)

[0042] The autothermal reforming reaction is a reforming process in which hydrocarbons are reacted with water (steam) and oxygen to produce synthesis gas. The hydrocarbons are first oxidized by oxygen, and then the oxidized hydrocarbons are steam reformed with water (steam). For example, the autothermal reforming reaction of methane includes methane oxidation and steam reforming, and the main chemical reactions that occur include:

[0043] Methane oxidation: CH4+2O2=CO2+2H2O (v);

[0044] CH4+O2=CO2+2H2 (vi);

[0045] Steam reforming: See (i) and (ii).

[0046] According to some embodiments of the present invention, preferably, when the reaction occurring in the first contact is an autothermal reforming reaction, in step (1), the material participating in the first contact also includes oxygen.

[0047] According to some embodiments of the present invention, in step (1), the reformed synthetic gas includes hydrogen (H2) and carbon monoxide (CO); it may also contain at least one of CO2, CH4, water (water vapor), nitrogen and argon; preferably, the reformed synthetic gas contains hydrogen, carbon monoxide and carbon dioxide.

[0048] According to some embodiments of the present invention, preferably, the content of H2 in the reformed synthetic gas is 60-80% by volume, preferably 70-80% by volume.

[0049] According to some embodiments of the present invention, preferably, the content of CO2 in the reformed synthetic gas is 5-10% by volume, preferably 5-8% by volume.

[0050] According to some embodiments of the present invention, preferably, the content of CO in the reformed synthetic gas is 10-15% by volume, preferably 12-14% by volume.

[0051] According to some embodiments of the present invention, in the reformed synthetic gas, n(H2-CO2) / n(CO+CO2)=3-4; wherein n(H2-CO2) is the difference between the molar amounts of H2 and CO2, n(CO+CO2) is the sum of the molar amounts of CO and CO2, and n(H2-CO2) / n(CO+CO2) is the ratio obtained by dividing the difference between the molar amounts of H2 and CO2 by the sum of the molar amounts of CO and CO2.

[0052] According to some embodiments of the present invention, preferably, the conditions for the first contact include: a temperature of 850-1150°C, preferably 900-1000°C; a pressure of 1-8 MPa, preferably 2-3 MPa; a volume space velocity of 5000-15000 h -1 , preferably 8000-12000h -1 .

[0053] According to some embodiments of the present invention, preferably, the molar ratio of the hydrocarbon-containing stream to water is 1:1-2.

[0054] According to some embodiments of the present invention, in order to effectively utilize the excess H2 in the reformed synthetic gas, realize the resource utilization of CO2, and increase the content of CO in the synthesis gas raw material, in step (2), the reformed synthetic gas is divided into A gas and B gas, and the A gas is contacted with carbon dioxide for a second time in the presence of a reverse water vapor shift catalyst to obtain a reverse water vapor shift synthesis gas; then in step (3), the B gas is mixed with the reverse water vapor shift synthesis gas to obtain a synthesis gas raw material. Taking the total flow rate of the reformed synthetic gas as 100%, the sum of the flow rates of the A gas and the B gas is 100%. The present invention has no particular limitation on the amount of the A gas, as long as at least a portion (greater than 0%) of the reformed synthetic gas is contacted with carbon dioxide for a second time in the presence of a reverse water vapor shift catalyst, the purpose of the present invention can be achieved to a certain extent. Preferably, the A gas is all the reformed synthetic gas, and the flow rate of the B gas is zero.

[0055] According to some embodiments of the present invention, preferably, the reaction occurring in the second contacting comprises a reverse water gas shift reaction; more preferably, the conditions of the second contacting comprise: a temperature of 500-800°C, preferably 600-700°C, a pressure of 1-5MPa, preferably 2-5MPa; a volume space velocity of 5000-40000h -1 , preferably 10000-20000h -1 .

[0056] According to some embodiments of the present invention, preferably, the amount of carbon dioxide is 10-15% by volume, preferably 12-14% by volume, based on the total amount of A gas and carbon dioxide (when A gas is all the recombined synthesized gas, it is based on the total amount of the recombined synthesized gas and carbon dioxide). The amount of carbon dioxide used within the above preferred range is conducive to improving the utilization rate of H2, thereby increasing the production of methanol.

[0057] According to some embodiments of the present invention, since the reverse water vapor shift reaction is an endothermic reaction, in order to improve the single-pass conversion rate of CO2, preferably, the temperature of the carbon dioxide is 500-800°C, more preferably 600-700°C. Conventional heating equipment in the art can be used to heat the carbon dioxide to the temperature. In order to reduce energy consumption during the reaction, it is further preferred that in step (3), the mixing process includes: firstly dividing the reverse water vapor shift synthesis gas into a first gas stream and a second gas stream, and performing heat exchange between the first gas stream and the carbon dioxide to heat the carbon dioxide to the temperature.

[0058] According to some embodiments of the present invention, the reverse water steam shift synthesis gas contains hydrogen, carbon monoxide and carbon dioxide; preferably, in the reverse water steam shift synthesis gas, n(H2-CO2) / n(CO+CO2)=2.1-2.5; more preferably, in the reverse water steam shift synthesis gas, n(H2-CO2) / n(CO+CO2)=2.1-2.3.

[0059] According to some embodiments of the present invention, in step (2), the reverse water gas shift catalyst can be a conventional catalyst suitable for reverse water gas shift reaction in the art, for example, a Ni / MgAl2O4 catalyst, a Pt / TiO2 catalyst, a Pd / CeO2 / Al2O3 catalyst, a Cu / SiO2 catalyst, a perovskite catalyst (BaCe x Zr 0.8-x Y 0.16 Zn 0.04 O3、BaZr 0.8 Y 0.2 O3、BaZr 0.8 Y 0.16 Zn 0.04 O3), etc., the present invention has no particular limitation on this, and conventional catalysts suitable for reverse water gas shift reaction in the art can achieve the purpose of the present invention to a certain extent. The reverse water gas shift catalyst can also be prepared by conventional methods in the art, and the present invention also has no particular limitation on this.

[0060] In order to improve catalytic activity and high-temperature stability and reduce costs, and further increase the production of methanol, preferably, based on the total amount of the reverse water steam shift catalyst, the reverse water steam shift catalyst contains 2-8 weight% of Cr2O3, 5-16 weight% of TiO2, 20-30 weight% of MgO and 50-70 weight% of Al2O3; the reverse water steam shift catalyst contains a magnesium aluminum spinel phase.

[0061] According to some embodiments of the present invention, the reverse water vapor shift catalyst contains a magnesium aluminum spinel phase. The magnesium aluminum spinel phase in the catalyst can not only serve as a carrier of the active component Cr2O3, but also can work together with other components in the catalyst to provide partial catalytic activity, so that the catalyst has high reverse water vapor shift activity and good high-temperature stability. Preferably, in the XRD spectrum of the reverse water vapor shift catalyst, diffraction peaks of MgAl2O4 appear at 2θ of 19°, 37°, 45°, 60° and 66°. More preferably, in the XRD spectrum of the reverse water vapor shift catalyst, no diffraction peak of MgO appears, which is beneficial to improving the reverse water vapor shift activity and high-temperature stability of the catalyst.

[0062] According to some embodiments of the present invention, preferably, the reverse water vapor shift catalyst also contains a magnesium titanate phase; more preferably, the magnesium titanate phase is a magnesium metatitanate phase; in the XRD spectrum of the reverse water vapor shift catalyst, diffraction peaks of magnesium metatitanate (MgTiO3) appear at 2θ of 21°, 24°, 33°, 35°, 49° and 53.5°. The above preferred embodiments can further improve the strength of the catalyst while ensuring that the catalyst has high reverse water vapor shift activity and high temperature stability.

[0063] According to some embodiments of the present invention, preferably, in the reverse water gas shift catalyst, the molar ratio of Al2O3 to TiO2 is 1-8: 1, preferably 1-5: 1. The reverse water gas shift catalyst has the above-mentioned specific molar relationship, which is conducive to further promoting the formation of MgAl2O4 and MgTiO3 phases in the catalyst.

[0064] According to some embodiments of the present invention, preferably, in the reverse water gas shift catalyst, the ratio of the sum of the molar amounts of Al2O3, TiO2 and MgO to the molar amount of Cr2O3 is 30-100: 1, preferably 30-50: 1. The reverse water gas shift catalyst has the above-mentioned specific molar relationship, which is conducive to further promoting the high dispersion of Cr2O3 in the catalyst and avoiding sintering and deactivation of nano-Cr2O3 particles at high temperature.

[0065] According to some embodiments of the present invention, preferably, the specific surface area of ​​the reverse water gas shift catalyst is 180-300m 2 / g, preferably 200-250m 2 / g. The reverse water gas shift catalyst has a high specific surface area, which is conducive to promoting the high dispersion of the active component Cr2O3 on the Al / Mg / Ti oxide carrier, further improving the interaction between the active component Cr2O3 and the carrier, and improving the stability of nano Cr2O3 particles on the carrier surface, so as to further improve the catalytic activity and high temperature stability of the catalyst in the reverse water gas shift reaction.

[0066] According to some embodiments of the present invention, preferably, the method for preparing the reverse water gas shift catalyst comprises the following steps:

[0067] (a) kneading an alumina binder, a magnesium-containing compound, a titanium-containing compound, a chromium-containing compound and water to obtain a mixture;

[0068] (b) extruding the mixture, and performing a first drying and a first calcination to obtain a catalyst precursor A;

[0069] (c) subjecting the catalyst precursor A to hydrothermal aging, and then subjecting it to a second drying and a second calcination to obtain a catalyst precursor B;

[0070] (d) contacting the catalyst precursor B with a reducing gas containing hydrogen for a third time to obtain a reverse water gas shift catalyst;

[0071] The magnesium-containing compound is magnesium hydroxide, which is in nano-flake form and has an average particle size of 100-500 nm; the alumina binder is calculated as Al2O3, the magnesium-containing compound is calculated as MgO, and the titanium-containing compound is calculated as TiO2. The feeding amounts of the alumina binder, the magnesium-containing compound and the titanium-containing compound satisfy that: the molar amount of MgO is greater than the molar amount of Al2O3, and the ratio of the sum of the molar amounts of Al2O3 and TiO2 to the molar amount of MgO is 1-1.1:1.

[0072] According to some embodiments of the present invention, the method adopts a specific formula, and controls the amount relationship of each raw material, and cooperates with hydrothermal aging to prepare the reverse water gas shift catalyst.

[0073] According to some embodiments of the present invention, there is no particular restriction on the manner of introducing the components into the reverse water gas shift catalyst, and conventional introduction methods in the art may be adopted, such as kneading, impregnation, co-precipitation, etc., as long as the composition of the reverse water gas shift catalyst of the present invention can be obtained.

[0074] According to some embodiments of the present invention, the method uses a kneading method to introduce various components in the reverse water vapor shift catalyst. In step (a), the various raw materials constituting the reverse water vapor shift catalyst are mixed by kneading. Water is added during the kneading to form a dough-like billet with elasticity. Preferably, the amount of water used is 10-20% by weight of the total weight of the alumina binder, magnesium-containing compound, titanium-containing compound and chromium-containing compound. During the kneading process, the amount of raw materials of various components can be sufficient to obtain the composition of the reverse water vapor shift catalyst of the present invention.

[0075] According to some embodiments of the present invention, preferably, the alumina binder is calculated as Al2O3, the magnesium-containing compound is calculated as MgO, the titanium-containing compound is calculated as TiO2, and the chromium-containing compound is calculated as Cr2O3, and the feeding amounts of the alumina binder, the magnesium-containing compound, the titanium-containing compound and the chromium-containing compound satisfy: the molar ratio of Al2O3 to TiO2 is 1-8:1, preferably 1-5:1.

[0076] According to some embodiments of the present invention, preferably, the alumina binder is calculated as Al2O3, the magnesium-containing compound is calculated as MgO, the titanium-containing compound is calculated as TiO2, and the chromium-containing compound is calculated as Cr2O3, and the feeding amounts of the alumina binder, the magnesium-containing compound, the titanium-containing compound and the chromium-containing compound satisfy: the ratio of the sum of the molar amounts of Al2O3, TiO2 and MgO to the molar amount of Cr2O3 is 30-100:1, preferably 30-50:1.

[0077] According to some embodiments of the present invention, preferably, in step (a), the alumina binder is selected from at least one of pseudo-boehmite, amorphous aluminum hydroxide and boehmite, preferably pseudo-boehmite.

[0078] According to some embodiments of the present invention, preferably, the titanium-containing compound is selected from at least one of metatitanic acid hydrate, metatitanic acid and nano titanium dioxide, preferably metatitanic acid hydrate.

[0079] According to some embodiments of the present invention, preferably, the chromium-containing compound is selected from at least one of chromium nitrate, chromium acetate and chromium oxalate, preferably chromium nitrate and / or chromium acetate.

[0080] According to some embodiments of the present invention, in step (b), the mixture is extruded, and first dried and first calcined to obtain catalyst precursor A. This step is used to shape the mixture; the first drying and first calcining steps can convert the components in the shaped product into oxide forms.

[0081] According to some embodiments of the present invention, preferably, the first drying conditions include: a temperature of 80-250° C., preferably 100-200° C.; and a time of 1-25 h, preferably 2-20 h.

[0082] According to some embodiments of the present invention, preferably, the conditions for the first calcination include: a temperature of 300-700° C., preferably 400-600° C.; and a time of 1-10 h, preferably 3-8 h.

[0083] According to some embodiments of the present invention, in step (c), the catalyst precursor A is subjected to hydrothermal aging, and then subjected to a second drying and a second calcination to obtain a catalyst precursor B. The hydrothermal aging step can optimize the catalyst precursor A to remove free MgO in the catalyst, and at the same time cooperate with the specific formulation of the method, and control the relationship between the amounts of each raw material to achieve the formation of the magnesium aluminum spinel phase. The hydrothermal aging can be to place the catalyst precursor A in a closed container and immerse it in water, and heat the container so that the material therein is hydrothermally aged under autogenous pressure.

[0084] According to some embodiments of the present invention, preferably, the hydrothermal aging conditions include: a temperature of 100-200° C., preferably 100-150° C.; and a time of 4-12 h, preferably 6-10 h.

[0085] According to some embodiments of the present invention, in step (c), the second drying and second calcining steps are used to remove moisture from the material obtained after hydrothermal aging and convert various components in the material into oxide forms to obtain catalyst precursor B.

[0086] According to some embodiments of the present invention, preferably, the second drying conditions include: a temperature of 80-150° C., preferably 100-120° C.; and a time of 2-25 h, preferably 2-20 h.

[0087] According to some embodiments of the present invention, preferably, the conditions of the second calcination include: a temperature of 400-900° C., preferably 500-800° C.; and a time of 1-10 h, preferably 3-8 h.

[0088] According to some embodiments of the present invention, in step (d), the catalyst precursor B is contacted with a reducing gas containing hydrogen for a third time to obtain a reverse water gas shift catalyst. During the third contact, CrO3 contained in the catalyst precursor B is reduced to Cr2O3.

[0089] According to some embodiments of the present invention, there is no particular limitation on the reducing gas containing hydrogen, as long as the preparation of the reverse water gas shift catalyst having the above-mentioned components can be achieved. The reducing gas can be a reducing gas conventionally used in the art for activating the reverse water gas shift catalyst, for example, it can be pure hydrogen or a reducing gas containing hydrogen (for example, a mixed gas of hydrogen and an inert gas, in which the content of hydrogen can be 10-90% by volume; the inert gas can be at least one of nitrogen, argon, neon and helium). The reducing gas can also be the feed gas in the reverse water gas shift reaction.

[0090] According to some embodiments of the present invention, preferably, the reducing gas is the reformed synthetic gas obtained in step (1). The reverse water gas shift catalyst does not need to undergo additional activation and reduction operations before the reverse water gas shift reaction. During the reverse water gas shift reaction, activation and reduction can be achieved under the action of the reducing gas H2 in the reformed synthetic gas. Existing metal-based reverse water gas shift catalysts require additional activation and reduction operations before use to reduce metal oxides to metals, thereby achieving the designed activity. If only the reformed synthetic gas is reduced, a high activity cannot be achieved in the initial stage of the reaction, and a long activity improvement process is required, wasting the reformed synthetic gas.

[0091] According to some embodiments of the present invention, preferably, the conditions for the third contact include: temperature of 500-800°C, preferably 600-700°C; pressure of 1-5MPa, preferably 2-5MPa; volume space velocity of 5000-40000h -1 , preferably 10000-20000h -1 .

[0092] According to some embodiments of the present invention, in order to reduce energy consumption during the reaction process, in step (3), the B gas is mixed with the reverse water vapor shift synthesis gas to obtain a synthesis gas raw material. Preferably, the mixing process includes: firstly dividing the reverse water vapor shift synthesis gas into a first gas stream and a second gas stream, the first gas stream is heat exchanged with carbon dioxide to obtain a first gas stream after heat exchange and carbon dioxide after heat exchange; then the second gas stream, the first gas stream after heat exchange and the B gas are collected to obtain a synthesis gas raw material; wherein the carbon dioxide after heat exchange is used as the carbon dioxide in step (2). Taking the total flow rate of the reverse water vapor shift synthesis gas as 100%, the sum of the flow rates of the first gas stream and the second gas stream is 100%. The present invention has no particular limitation on the amount of the first gas stream, as long as at least part (greater than 0%) of the reverse water vapor shift synthesis gas is heat exchanged with carbon dioxide, the purpose of the present invention can be achieved to a certain extent. Preferably, the first gas stream is all the reverse water vapor shift synthesis gas, and the flow rate of the second gas stream is zero.

[0093] According to some embodiments of the present invention, in step (3), the synthesis gas raw material contains hydrogen, carbon monoxide and carbon dioxide; preferably, in the synthesis gas raw material, n(H2-CO2) / n(CO+CO2)=2.1-2.5; more preferably, in the synthesis gas raw material, n(H2-CO2) / n(CO+CO2)=2.1-2.3.

[0094] According to some embodiments of the present invention, preferably, in step (3), the conditions of the methanol synthesis reaction include: a reaction temperature of 200-300°C, preferably 230-240°C; a pressure of 3-8MPa, preferably 4-6MPa; a volume space velocity of 5000-20000h -1 , preferably 8000-12000h -1 .

[0095] According to some embodiments of the present invention, preferably, the method further comprises the steps of purifying and desulfurizing the hydrocarbon-containing raw material to obtain a hydrocarbon-containing flow; more preferably, the hydrocarbon-containing raw material is coke oven gas.

[0096] According to some embodiments of the present invention, preferably, the method further comprises separating water from the synthesis gas raw material before conducting the methanol synthesis reaction, returning the separated water obtained to step (1), and subjecting the obtained raw material to a methanol synthesis reaction to obtain a synthetic product containing methanol.

[0097] According to some embodiments of the present invention, preferably, the method further comprises distilling the synthetic material containing methanol to obtain a methanol product.

[0098] According to a particularly preferred embodiment of the present invention, the method for producing methanol comprises:

[0099] (1-1) purifying and desulfurizing a hydrocarbon-containing raw material to obtain a hydrocarbon-containing stream;

[0100] (2-1) contacting the hydrocarbon-containing stream with water to obtain a reformed synthetic gas;

[0101] (3-1) The reformed synthesized gas is divided into a gas A and a gas B, and the gas A is brought into a second contact with carbon dioxide in the presence of a reverse water vapor shift catalyst to obtain a reverse water vapor shift synthesis gas; wherein the gas A is the entire reformed synthesized gas, and the flow rate of the gas B is zero.

[0102] (4-1) Mixing the B gas with the reverse water vapor shift synthesis gas to obtain a synthesis gas raw material; wherein the mixing process includes: firstly dividing the reverse water vapor shift synthesis gas into a first gas flow and a second gas flow, performing heat exchange between the first gas flow and carbon dioxide to obtain a first gas flow after heat exchange and carbon dioxide after heat exchange; then combining the second gas flow, the first gas flow after heat exchange and the B gas to obtain a synthesis gas raw material; wherein the first gas flow is the entire reverse water vapor shift synthesis gas, and the flow rate of the second gas flow is zero.

[0103] (5-1) Separating the water from the synthesis gas raw material, returning the separated water to step (2-1), subjecting the raw material to a methanol synthesis reaction, and obtaining a synthetic product containing methanol.

[0104] (6-1) The synthetic product containing methanol is distilled to obtain a methanol product.

[0105] Wherein, in step (1-1), the hydrocarbon-containing raw material is coke oven gas; in step (2-1), the water is separated water; and the carbon dioxide after heat exchange is used as the carbon dioxide in step (3-1).

[0106] A second aspect of the present invention provides a system for producing methanol, which includes a reforming reaction unit, a reverse water gas shift reaction unit, an optional synthesis gas mixing unit and a methanol synthesis reaction unit connected in sequence.

[0107] According to some embodiments of the present invention, preferably, a reverse water steam shift catalyst is provided in the reverse water steam shift reaction unit. The reverse water steam shift catalyst can be selected with reference to the above and will not be described in detail here.

[0108] According to some embodiments of the present invention, more preferably, based on the total amount of the reverse water gas shift catalyst, the reverse water gas shift catalyst comprises 2-8 wt% Cr2O3, 5-16 wt% TiO2, 20-30 wt% MgO and 50-70 wt% Al2O3; the reverse water gas shift catalyst contains a magnesium aluminum spinel phase. The preparation method of the reverse water gas shift catalyst can also be selected with reference to the above, and will not be repeated here.

[0109] According to some embodiments of the present invention, preferably, the system further comprises a pretreatment unit, wherein the pretreatment unit is used to purify and desulfurize the hydrocarbon-containing feedstock to obtain a hydrocarbon-containing flow, and send the hydrocarbon-containing flow to the reforming reaction unit.

[0110] According to some embodiments of the present invention, preferably, the system further comprises a heat exchange unit, and the heat exchange unit is used for performing heat exchange between the reverse water gas shift synthesis gas and carbon dioxide.

[0111] According to some embodiments of the present invention, preferably, the system further comprises a separation unit, and the separation unit is used to separate water from the synthesis gas feedstock.

[0112] According to some embodiments of the present invention, preferably, the system further comprises a distillation unit, and the distillation unit is used to distill the synthetic material containing methanol to obtain a methanol product.

[0113] According to a particularly preferred embodiment of the present invention, the system for producing methanol comprises a reforming reaction unit, a reverse water vapor shift reaction unit, an optional synthesis gas mixing unit and a methanol synthesis reaction unit connected in sequence; a reverse water vapor shift catalyst is arranged in the reverse water vapor shift reaction unit, and based on the total amount of the reverse water vapor shift catalyst, the reverse water vapor shift catalyst comprises 2-8 wt% of Cr2O3, 5-16 wt% of TiO2, 20-30 wt% of MgO and 50-70 wt% of Al2O3; the reverse water vapor shift catalyst contains a magnesium aluminum spinel phase; the system also comprises a pretreatment unit, which is used to purify and desulfurize the hydrocarbon-containing feedstock to obtain a hydrocarbon-containing flow, and send the hydrocarbon-containing flow into the reforming reaction unit; the system also comprises a heat exchange unit, which is used to heat exchange the reverse water vapor shift synthesis gas with carbon dioxide; the system also comprises a separation unit, which is used to separate water from the synthesis gas feedstock; the system also comprises a distillation unit, which is used to distill the synthetic product containing methanol to obtain a methanol product.

[0114] The method and system for producing methanol provided by the present invention are further described in detail below in conjunction with the accompanying drawings.

[0115] The present invention illustratively provides a method and system schematic diagram of producing methanol in an embodiment, such as Figure 1 As shown, the system includes a pretreatment unit I, a reforming reaction unit II, a reverse water gas shift reaction unit III, a synthesis gas mixing unit V, a methanol synthesis reaction unit VII and a distillation unit VIII. The method includes:

[0116] (S1-1) sending the hydrocarbon-containing raw material 1 to the pretreatment unit I for purification and desulfurization to obtain a hydrocarbon-containing stream 2;

[0117] (S1-2) In the reforming reaction unit II, the hydrocarbon-containing stream 2 is first contacted with water 15 to obtain a reformed synthetic gas 16;

[0118] (S1-3) dividing the reformed synthesis gas 16 into an A gas 3 and a B gas 4, sending the B gas 4 to a synthesis gas mixing unit V, and in a reverse water steam shift reaction unit III, bringing the A gas 3 and the carbon dioxide 14 into a second contact with a reverse water steam shift catalyst to obtain a reverse water steam shift synthesis gas 17;

[0119] (S1-4) In the synthesis gas mixing unit V, the B gas 4 is mixed with the reverse water steam shift synthesis gas 17 to obtain a synthesis gas feedstock 9;

[0120] (S1-5) In the methanol synthesis reaction unit VII, the synthesis gas raw material 9 is subjected to a methanol synthesis reaction to obtain a synthetic product 12 containing methanol;

[0121] (S1-6) In the distillation unit VIII, the synthetic product 12 containing methanol is distilled to obtain a methanol product 13.

[0122] The present invention illustratively provides a method and system schematic diagram of producing methanol in a preferred embodiment, such as Figure 2 As shown, the system includes a pretreatment unit I, a reforming reaction unit II, a reverse water vapor shift reaction unit III, a heat exchange unit IV, a synthesis gas mixing unit V, a methanol synthesis reaction unit VII and a distillation unit VIII. The method includes:

[0123] (S2-1) sending the hydrocarbon-containing raw material 1 to the pretreatment unit I for purification and desulfurization to obtain a hydrocarbon-containing stream 2;

[0124] (S2-2) In the reforming reaction unit II, the hydrocarbon-containing stream 2 is first contacted with water 15 to obtain a reformed synthetic gas 16;

[0125] (S2-3) dividing the reformed synthesis gas 16 into an A gas 3 and a B gas 4, sending the B gas 4 to a synthesis gas mixing unit V, and in a reverse water steam shift reaction unit III, bringing the A gas 3 and the heat-exchanged carbon dioxide 7 into a second contact with a reverse water steam shift catalyst to obtain a reverse water steam shift synthesis gas 17;

[0126] (S2-4) dividing the reverse water vapor shift synthesis gas 17 into a first gas stream 5 and a second gas stream 6, sending the second gas stream 6 to a synthesis gas mixing unit V, and exchanging heat between the first gas stream 5 and the carbon dioxide 14 in a heat exchange unit IV to obtain heat-exchanged carbon dioxide 7 and heat-exchanged first gas stream 8;

[0127] (S2-5) In the synthesis gas mixing unit V, the second gas stream 6, the first gas stream 8 after heat exchange and the B gas 4 are combined to obtain a synthesis gas raw material 9;

[0128] (S2-6) In the methanol synthesis reaction unit VII, the synthesis gas raw material 9 is subjected to a methanol synthesis reaction to obtain a synthetic product 12 containing methanol;

[0129] (S2-7) In the distillation unit VIII, the synthetic product 12 containing methanol is distilled to obtain a methanol product 13.

[0130] The present invention illustratively provides another preferred embodiment of a method and system for producing methanol, such as Figure 3 As shown, the system includes a pretreatment unit I, a reforming reaction unit II, a reverse water vapor shift reaction unit III, a heat exchange unit IV, a synthesis gas mixing unit V, a methanol synthesis reaction unit VII and a distillation unit VIII. The method includes:

[0131] (S3-1) sending the hydrocarbon-containing raw material 1 to the pretreatment unit I for purification and desulfurization to obtain a hydrocarbon-containing stream 2;

[0132] (S3-2) In the reforming reaction unit II, the hydrocarbon-containing stream 2 is first contacted with water 15 to obtain a reformed synthetic gas 16;

[0133] (S3-3) in the reverse water gas shift reaction unit III, the reformed synthetic gas 16 (i.e., the A stream 3 is the entire reformed synthetic gas 16, and the flow rate of the B stream 4 is zero) and the heat-exchanged carbon dioxide 7 are brought into second contact with the reverse water gas shift catalyst to obtain the reverse water gas shift synthesis gas 17;

[0134] (S3-4) dividing the reverse water vapor shift synthesis gas 17 into a first gas stream 5 and a second gas stream 6, sending the second gas stream 6 to the synthesis gas mixing unit V, and exchanging heat between the first gas stream 5 and the carbon dioxide 14 in the heat exchange unit IV to obtain the heat-exchanged carbon dioxide 7 and the heat-exchanged first gas stream 8;

[0135] (S3-5) In the synthesis gas mixing unit V, the second gas stream 6 and the first gas stream 8 after heat exchange are combined to obtain a synthesis gas raw material 9;

[0136] (S3-6) In the methanol synthesis reaction unit VII, the synthesis gas raw material 9 is subjected to a methanol synthesis reaction to obtain a synthetic product 12 containing methanol;

[0137] (S3-7) In the distillation unit VIII, the synthetic product 12 containing methanol is distilled to obtain a methanol product 13.

[0138] The present invention illustratively provides another preferred embodiment of a method and system for producing methanol, such as Figure 4 As shown, the system includes a pretreatment unit I, a reforming reaction unit II, a reverse water vapor shift reaction unit III, a heat exchange unit IV, a methanol synthesis reaction unit VII and a distillation unit VIII. The method includes:

[0139] (S4-1) sending the hydrocarbon-containing raw material 1 to the pretreatment unit I for purification and desulfurization to obtain a hydrocarbon-containing stream 2;

[0140] (S4-2) in the reforming reaction unit II, the hydrocarbon-containing stream 2 is first contacted with water 15 to obtain a reformed synthetic gas 16;

[0141] (S4-3) in the reverse water gas shift reaction unit III, the reformed synthetic gas 16 (i.e., the A stream 3 is the entire reformed synthetic gas 16, and the flow rate of the B stream 4 is zero) and the heat-exchanged carbon dioxide 7 are brought into second contact with the reverse water gas shift catalyst to obtain the reverse water gas shift synthesis gas 17;

[0142] (S4-4) In the heat exchange unit IV, the reverse water vapor shift synthesis gas 17 (i.e., the first airflow 5 is the entire reverse water vapor shift synthesis gas 17, and the flow rate of the second airflow 6 is zero) is heat exchanged with the carbon dioxide 14 to obtain the heat-exchanged carbon dioxide 7 and the heat-exchanged first airflow 8;

[0143] (S4-5) In the methanol synthesis reaction unit VII, the first gas stream 8 after heat exchange is used as a synthesis gas raw material 9 to perform a methanol synthesis reaction to obtain a synthetic product 12 containing methanol;

[0144] (S4-6) In the distillation unit VIII, the synthetic product 12 containing methanol is distilled to obtain a methanol product 13.

[0145] The present invention illustratively provides another preferred embodiment of a method and system for producing methanol, such as Figure 5 As shown, the system includes a pretreatment unit I, a reforming reaction unit II, a reverse water vapor shift reaction unit III, a heat exchange unit IV, a separation unit VI, a methanol synthesis reaction unit VII and a distillation unit VIII. The method includes:

[0146] (S5-1) sending the hydrocarbon-containing raw material 1 to the pretreatment unit I for purification and desulfurization to obtain a hydrocarbon-containing stream 2;

[0147] (S5-2) In the reforming reaction unit II, the hydrocarbon-containing stream 2 is first contacted with the separated water 10 to obtain a reformed synthetic gas 16;

[0148] (S5-3) in the reverse water gas shift reaction unit III, the reformed synthetic gas 16 (i.e., the A stream 3 is the entire reformed synthetic gas 16, and the flow rate of the B stream 4 is zero) and the heat-exchanged carbon dioxide 7 are brought into second contact with the reverse water gas shift catalyst to obtain the reverse water gas shift synthesis gas 17;

[0149] (S5-4) In the heat exchange unit IV, the reverse water vapor shift synthesis gas 17 (i.e., the first airflow 5 is the entire reverse water vapor shift synthesis gas 17, and the flow rate of the second airflow 6 is zero) is heat exchanged with the carbon dioxide 14 to obtain the heat-exchanged carbon dioxide 7 and the heat-exchanged first airflow 8;

[0150] (S5-5) using the first gas stream 8 after heat exchange as a synthesis gas raw material 9, and then separating water in the synthesis gas raw material 9 in a separation unit VI, returning the obtained separated water 10 to step (S5-2), and sending the raw material 11 to a methanol synthesis reaction unit VII for a methanol synthesis reaction to obtain a synthetic product 12 containing methanol;

[0151] (S5-6) In the distillation unit VIII, the synthetic product 12 containing methanol is distilled to obtain a methanol product 13.

[0152] The present invention exemplarily provides a process flow chart of producing methanol from coke oven gas in the prior art, such as Figure 6 As shown, the process is that the coke oven gas is pretreated (first purified to remove tar and remove benzene and naphthalene, then subjected to desulfurization processes such as wet desulfurization and hydrodesulfurization to remove inorganic sulfur and organic sulfur, and then reformed (steam reforming and / or autothermal reforming) to convert methane, low-carbon alkanes, etc. in the hydrocarbon-containing flow into a reformed synthetic gas, and then the reformed synthetic gas is directly used as a synthesis gas raw material for a methanol synthesis reaction. The H2 content in the reformed synthetic gas is excessive, far higher than the gas modulus n(H2-CO2) / n(CO+CO2)=2 required for the synthesis gas to produce methanol. The excess H2 in the reformed synthetic gas does not participate in the methanol synthesis reaction, so that the excess H2 is wasted. The method for producing methanol provided by the present invention adds CO2 to the reformed synthetic gas, and in the presence of a reverse water vapor shift catalyst, CO2 and the excess H2 in the reformed synthetic gas undergo a reverse water vapor shift reaction to generate CO and H2O, while fully utilizing the reformed synthetic gas. The excess H2 in the recombined syngas increases the CO content while consuming CO2, thus realizing the resource utilization of CO2. Preferably, by controlling the amount of CO2 added and the type of catalyst and process conditions of the reverse water vapor shift, the gas modulus in the syngas raw material meets the needs of subsequent methanol synthesis. Since the amount of syngas raw material required for the subsequent methanol synthesis reaction is increased, the output of methanol will also increase accordingly. In addition, preferably, before the methanol synthesis reaction is carried out, the H2O in the syngas raw material can also be separated to avoid excessive H2O content in the CO2 and H2 methanol production process, avoid high subsequent separation costs, and return the separated water to step (1) to react with the hydrocarbon-containing stream, making full use of the raw materials in the reaction process. Furthermore, preferably, by heating carbon dioxide through heat exchange with the reverse water vapor shift syngas, the energy consumption of the system can also be effectively reduced.

[0153] In the present invention, the pressures are all gauge pressures.

[0154] The present invention will be described in detail below through examples.

[0155] In the following preparation examples, embodiments and comparative examples, unless otherwise specified, all raw materials can be obtained from commercial sources. Among them, metatitanic acid hydrate was purchased from Shanghai Qiandu Industrial Co., Ltd.

[0156] The composition of the catalyst was determined by a ZSX Primus II X-ray fluorescence spectrometer (XRF) from Rigaku;

[0157] The XRD spectrum of the catalyst was measured by an X-ray diffractometer. The powder X-ray diffractometer was purchased from Bruker Company and its model was D8 advance.

[0158] The specific surface area of ​​the catalyst was measured by a nitrogen physical adsorption instrument, which was purchased from Micromeritics Company and has a model of tristarII 3020-M.

[0159] The catalyst strength was measured using a particle strength tester from VINCI.

[0160] Preparation Example

[0161] This preparation example is used to illustrate the reverse water gas shift catalyst and its preparation method

[0162] (a) 350 g of pseudo-boehmite (Al2O3 content of 70 wt%) and 165 g of magnesium hydroxide (flaky, average particle size of 200 nm, MgO content of 68 wt%) were mixed uniformly in the mixing hopper of an extruder.

[0163] (b) Weigh 100 g of titanic acid hydrate (TiO2 content: 50 wt%) and add it to the material obtained in step (a) and mix well.

[0164] (c) 155 g of Cr(NO3)3·9H2O is dissolved in 100 g of deionized water to prepare a solution, and then the obtained Cr(NO3)3 solution is added to the material obtained in step (b), and stirred in the mixing hopper of the extruder for 1 hour to mix evenly to obtain a mixture. The feeding amounts of pseudo-boehmite, magnesium hydroxide and metatitanic acid hydrate satisfy that the molar amount of MgO is greater than the molar amount of Al2O3, and the ratio of the sum of the molar amounts of Al2O3 and TiO2 to the molar amount of MgO is 1.09:1.

[0165] (d) The mixture obtained in step (c) is extruded on an extruder to obtain a molded sample with a diameter of 3 mm.

[0166] (e) The molded sample obtained in step (d) was dried at 120° C. for 2 h, and then calcined at 500° C. for 4 h to obtain a catalyst precursor A.

[0167] (f) The catalyst precursor A obtained in step (e) is placed in a hydrothermal reactor and hydrothermally aged at 100° C. for 6 h, and then the hydrothermally aged product is dried at 120° C. for 2 h, and then calcined at 800° C. for 4 h to obtain a catalyst precursor B.

[0168] (g) contacting the catalyst precursor B obtained in step (f) with a reformed synthetic gas (wherein the content of H2 is 75 vol%, the content of CH4 is 1.5 vol%, the content of CO2 is 6.5 vol%, the content of CO is 13.5 vol%, and the content of N2 is 3.5 vol%), wherein the contact conditions include: a temperature of 700°C, a pressure of 2 MPa, a volume space velocity of 10000 h -1, and obtain reverse water gas shift catalyst Z.

[0169] The composition of the catalyst is: 6.7 weight percent Cr2O3, 11.5 weight percent TiO2, 25.7 weight percent MgO and 56.1 weight percent Al2O3; wherein the molar ratio of Al2O3 to TiO2 is 3.8:1; and the ratio of the sum of the molar amounts of Al2O3, TiO2 and MgO to the molar amount of Cr2O3 is 30:1.

[0170] The XRD spectrum of the catalyst was compared with the standard spectrum, and it was determined that the catalyst had characteristic peaks of MgAl2O4 at 2θ of 19°, 37°, 45°, 60° and 66°, characteristic peaks of MgTiO3 at 2θ of 21°, 24°, 33°, 35°, 49° and 53.5°, and no diffraction peak of MgO, indicating that there was no MgO phase impurity in the catalyst. In addition, the XRD of the catalyst could not detect the Cr2O3 crystal phase, indicating that Cr2O3 was highly dispersed in the catalyst.

[0171] Nitrogen adsorption analysis showed that the specific surface area of ​​the catalyst was 238 m 2 / g.

[0172] The strength of the catalyst was 325 N / cm.

[0173] Examples 1-5 are used to illustrate the method and system for producing methanol provided by the present invention.

[0174] Example 1

[0175] This embodiment adopts Figure 4 The system for producing methanol shown in the figure comprises a pretreatment unit I, a reforming reaction unit II, a reverse water vapor shift reaction unit III, a heat exchange unit IV, a methanol synthesis reaction unit VII and a distillation unit VIII. The method for producing methanol is as follows:

[0176] (1) Coke oven gas is sent as a hydrocarbon-containing raw material to a pretreatment unit I for purification and desulfurization, and impurities such as tar, benzene, naphthalene, inorganic sulfur and organic sulfur in the coke oven gas are removed to obtain a hydrocarbon-containing stream (wherein the mass content of sulfur is less than 200 ppm), the composition of which (v / v) is: H2 / CH4 / CO2 / C2-C5 alkane / CO / N2=61% / 21% / 2.5% / 2% / 7.5% / 6%;

[0177] (2) In the reforming reaction unit II, the hydrocarbon-containing stream and water are subjected to steam reforming reaction, wherein the molar ratio of the hydrocarbon-containing stream to water is 1:1, and the reaction conditions are: temperature 900°C, pressure 2 MPa, volume space velocity 10000 h -1, and a reformed gas is obtained, whose composition (v / v) is: H2 / CH4 / CO2 / CO / N2=75% / 1.5% / 6.5% / 13.5% / 3.5%; n(H2-CO2) / n(CO+CO2)=3.4;

[0178] (3) In the reverse water gas shift reaction unit III, the recombined synthetic gas and the carbon dioxide after heat exchange (temperature is 600° C.) are contacted with the reverse water gas shift catalyst Z to carry out a reverse water gas shift reaction, wherein the gas composition (v / v) at the inlet of the reverse water gas shift reactor is H2 / CH4 / CO2 / CO / N2=69.8% / 1.4% / 13.0% / 12.6% / 3.3%; based on the total amount of the recombined synthetic gas and carbon dioxide, the amount of carbon dioxide used is 13% by volume, and the conditions for the reverse water gas shift reaction are: temperature of 700° C., pressure of 2 MPa, volume space velocity of 10000 h -1 , and obtain reverse water steam shift synthesis gas, whose composition (v / v) is: H2 / CH4 / CO2 / CO / N2=67.1% / 1.5% / 5.2% / 22.7% / 3.5%; n(H2-CO2) / n(CO+CO2)=2.2; CO2 conversion rate is 63.5%;

[0179] (4) feeding the reverse water vapor shift synthesis gas into a heat exchange unit IV, heating the carbon dioxide to 600° C. by heat exchange with the reverse water vapor shift synthesis gas, thereby obtaining heat-exchanged carbon dioxide and heat-exchanged reverse water vapor shift synthesis gas; feeding the heat-exchanged carbon dioxide into a reverse water vapor shift reaction unit III, and feeding the heat-exchanged reverse water vapor shift synthesis gas into a methanol synthesis reaction unit VII as a synthesis gas feedstock;

[0180] (5) In the methanol synthesis reaction unit VII, the synthesis gas raw material is subjected to a methanol synthesis reaction under the following reaction conditions: reaction temperature of 232°C, pressure of 5 MPa, and volumetric space velocity of 10,000 h -1 The resulting synthetic product containing methanol is then sent to the distillation unit VIII for distillation to obtain a methanol product, the yield of which is increased by 37.5%.

[0181] Example 2

[0182] This embodiment adopts Figure 5 The system for producing methanol shown in the figure comprises a pretreatment unit I, a reforming reaction unit II, a reverse water vapor shift reaction unit III, a heat exchange unit IV, a separation unit VI, a methanol synthesis reaction unit VII and a distillation unit VIII. The method for producing methanol is as follows:

[0183] (1) Coke oven gas is sent as a hydrocarbon-containing raw material to a pretreatment unit I for purification and desulfurization, and impurities such as tar, benzene, naphthalene, inorganic sulfur and organic sulfur in the coke oven gas are removed to obtain a hydrocarbon-containing stream (wherein the mass content of sulfur is less than 200 ppm, and the composition (v / v) is: H2 / CH4 / CO2 / C2-C5 alkane / CO / N2=61% / 21% / 2.5% / 2% / 7.5% / 6%);

[0184] (2) In the reforming reaction unit II, the hydrocarbon-containing stream and the separated water are subjected to steam reforming reaction, wherein the molar ratio of the hydrocarbon-containing stream to the separated water is 1:1, and the reaction conditions are: temperature 900°C, pressure 2 MPa, volume space velocity 10000 h -1 , and a reformed gas is obtained, whose composition (v / v) is: H2 / CH4 / CO2 / CO / N2=75% / 1.5% / 6.5% / 13.5% / 3.5%; n(H2-CO2) / n(CO+CO2)=3.4;

[0185] (3) In the reverse water gas shift reaction unit III, the recombined synthetic gas and the carbon dioxide after heat exchange (temperature is 600° C.) are contacted with the reverse water gas shift catalyst Z to carry out a reverse water gas shift reaction, wherein the gas composition (v / v) at the inlet of the reverse water gas shift reactor is H2 / CH4 / CO2 / CO / N2=69.8% / 1.4% / 13.0% / 12.6% / 3.3%; based on the total amount of the recombined synthetic gas and carbon dioxide, the amount of carbon dioxide used is 13% by volume, and the conditions for the reverse water gas shift reaction are: temperature of 700° C., pressure of 2 MPa, volume space velocity of 10000 h -1 , and obtain reverse water steam shift synthesis gas, whose composition (v / v) is: H2 / CH4 / CO2 / CO / N2=67.6% / 1.5% / 7.0% / 20.4% / 3.5%; n(H2-CO2) / n(CO+CO2)=2.2; CO2 conversion rate is 50%;

[0186] (4) feeding the reverse water vapor shift synthesis gas into the heat exchange unit IV, heating the carbon dioxide to 600° C. by heat exchange with the reverse water vapor shift synthesis gas, thereby obtaining heat-exchanged carbon dioxide and heat-exchanged reverse water vapor shift synthesis gas; feeding the heat-exchanged carbon dioxide into the reverse water vapor shift reaction unit III, and feeding the heat-exchanged reverse water vapor shift synthesis gas into the separation unit VI as a synthesis gas raw material;

[0187] (5) In the separation unit VI, water in the synthesis gas raw material is separated, the separated water is returned to step (2), and the raw material is sent to the methanol synthesis reaction unit VII;

[0188] (6) In the methanol synthesis reaction unit VII, the raw materials are subjected to a methanol synthesis reaction under the following reaction conditions: reaction temperature of 232°C, pressure of 5 MPa, and volumetric space velocity of 10,000 h -1 The resulting synthetic product containing methanol is then sent to the distillation unit VIII for distillation to obtain a methanol product, the yield of which is increased by 31.5%.

[0189] Example 3

[0190] According to the method of Example 1, the difference is that the reverse water gas shift catalyst Z is replaced by Ni / MgAl2O4 catalyst, and the remaining steps and conditions are the same as those of Example 1, and the methanol product is obtained, and its yield is increased by 15%. Among them, in the reverse water gas shift reaction unit III, the CO2 conversion rate is 30%.

[0191] Example 4

[0192] According to the method of Example 1, the difference is that in step (3), the amount of carbon dioxide used is 10% by volume based on the total amount of the reformed synthetic gas and carbon dioxide, and the remaining steps and conditions are the same as those of Example 1, and the methanol product is obtained, and its yield is increased by 28.8%. Among them, in the reverse water gas shift reaction unit III, the CO2 conversion rate is 65.2%.

[0193] Example 5

[0194] The method of Example 1 is followed, except that in step (3), the conditions for the reverse water vapor shift reaction are: temperature of 550° C., pressure of 1.0 MPa, volumetric space velocity of 35000 h -1 The remaining steps and conditions are the same as those in Example 1, and the methanol product is obtained, and its yield is increased by 27.5%. In the reverse water gas shift reaction unit III, the CO2 conversion rate is 40%.

[0195] Comparative Example 1

[0196] This comparative example adopts Figure 6 The system for producing methanol shown in the figure comprises a pretreatment unit I, a reforming reaction unit II, a methanol synthesis reaction unit VII and a distillation unit VIII. The method for producing methanol is as follows:

[0197] (1) Coke oven gas is sent as a hydrocarbon-containing raw material to a pretreatment unit I for purification and desulfurization, and impurities such as tar, benzene, naphthalene, inorganic sulfur and organic sulfur in the coke oven gas are removed to obtain a hydrocarbon-containing stream (wherein the mass content of sulfur is less than 200 ppm, and the composition (v / v) is: H2 / CH4 / CO2 / C2-C5 alkane / CO / N2=61% / 21% / 2.5% / 2% / 7.5% / 6%);

[0198] (2) In the reforming reaction unit II, the hydrocarbon-containing stream and water are subjected to steam reforming reaction, wherein the molar ratio of the hydrocarbon-containing stream to water is 1:1, and the reaction conditions are: temperature 900°C, pressure 2 MPa, volume space velocity 10000 h -1 , and a reformed gas is obtained, whose composition (v / v) is: H2 / CH4 / CO2 / CO / N2=67.1% / 1.5% / 5.2% / 22.7% / 3.5%; n(H2-CO2) / n(CO+CO2)=3.4;

[0199] (3) The reformed gas is sent to the methanol synthesis reaction unit VII for methanol synthesis reaction. The reaction conditions are: reaction temperature 232°C, pressure 5 MPa, volume space velocity 10000 h -1 The resulting synthetic product containing methanol is then sent to the distillation unit VIII for distillation to obtain a methanol product with an output of 22 tons / hour.

[0200] It can be seen from the above results that the method and system for producing methanol provided by the present invention can utilize the excess H2 in the reformed syngas, increase the CO content in the syngas raw material, achieve an increase in methanol production in the process of producing methanol from coke oven gas, increase enterprise benefits, effectively consume CO2, and realize the resource utilization of CO2.

[0201] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for producing methanol, characterized in that: The method comprises the following steps: (1) contacting a hydrocarbon-containing stream with water for the first time to obtain a reformed synthetic gas; the reformed synthetic gas contains hydrogen, carbon monoxide and carbon dioxide, wherein the content of H2 is 60-80% by volume; the content of CO2 is 5-10% by volume; the content of CO is 10-15% by volume; in the reformed synthetic gas, n(H2-CO2) / n(CO+CO2) = 3-4; (2) separating the reformed synthesis gas into a gas A and a gas B, and subjecting the gas A to a second contact with carbon dioxide in the presence of a reverse water gas shift catalyst to obtain a reverse water gas shift synthesis gas; Based on the total amount of the reverse water gas shift catalyst, the reverse water gas shift catalyst comprises 2-8 wt% of Cr2O3, 5-16 wt% of TiO2, 20-30 wt% of MgO and 50-70 wt% of Al2O3; the reverse water gas shift catalyst contains a magnesium aluminum spinel phase; (3) Mixing the B gas with the reverse water gas shift synthesis gas to obtain a synthesis gas feedstock; and subjecting the synthesis gas feedstock to a methanol synthesis reaction to obtain a synthetic product containing methanol.

2. The method according to claim 1, wherein: In step (2), the A stream of gas is all the recombined gas, and the flow rate of the B stream of gas is zero.

3. The method according to claim 2, wherein: In step (3), the mixing process includes: firstly dividing the reverse water vapor shift synthesis gas into a first gas stream and a second gas stream, performing heat exchange between the first gas stream and carbon dioxide to obtain a first gas stream after heat exchange and carbon dioxide after heat exchange; then combining the second gas stream, the first gas stream after heat exchange and the B gas to obtain a synthesis gas raw material; The carbon dioxide after heat exchange is used as the carbon dioxide in step (2).

4. The method according to claim 3, wherein: In step (3), the first airflow is all reverse water steam shift synthesis gas, and the flow rate of the second airflow is zero.

5. The method according to any one of claims 1 to 4, wherein: In step (1), the hydrocarbon-containing stream contains methane and / or hydrocarbons having a carbon number of not less than 2; And / or, the reaction occurring in the first contact includes a steam reforming reaction and / or an autothermal reforming reaction; and / or, the reformed synthetic gas contains hydrogen, carbon monoxide and carbon dioxide, wherein the content of H2 is 70-80% by volume; and / or, the content of CO2 is 5-8% by volume; and / or, the content of CO is 12-14% by volume; And / or, the conditions of the first contact include: temperature of 850-1150°C; pressure of 1-8 MPa; volume space velocity of 5000-15000 h -1 ; and / or, the molar ratio of the hydrocarbon-containing stream to water is 1:1-2.

6. The method according to claim 5, wherein: In step (1), the hydrocarbon-containing stream contains methane and / or low-carbon alkanes having a carbon number of 2 to 5; And / or, when the reaction occurring in the first contact is an autothermal reforming reaction, in step (1), the material participating in the first contact also includes oxygen; And / or, the conditions of the first contact include: temperature of 900-1000°C; pressure of 2-3 MPa; volume space velocity of 8000-12000 h -1 .

7. The method according to claim 6, wherein: In step (1), the hydrocarbon-containing flow further contains at least one of water, carbon monoxide, carbon dioxide, hydrogen, nitrogen and argon.

8. The method according to claim 7, wherein: In step (1), the mass content of sulfur in the hydrocarbon-containing stream is less than 200 ppm.

9. The method according to any one of claims 1 to 4, wherein: In step (2), the reaction occurring during the second contacting includes a reverse water vapor shift reaction; and / or, based on the total amount of A-gas and carbon dioxide, the amount of carbon dioxide used is 10-15% by volume; And / or, the temperature of the carbon dioxide is 500-800°C; And / or, the conditions of the second contact include: a temperature of 500-800° C. and a pressure of 1-5 MPa; Volume space velocity is 5000-40000h -1 ; And / or, the reverse water gas shift synthesis gas contains hydrogen, carbon monoxide and carbon dioxide.

10. The method according to claim 9, wherein: In step (2), the amount of carbon dioxide used is 12-14% by volume based on the total amount of A gas and carbon dioxide; And / or, the temperature of the carbon dioxide is 600-700°C; And / or, the conditions of the second contact include: a temperature of 600-700° C. and a pressure of 2-5 MPa; Volume space velocity is 10000-20000h -1 .

11. The method according to claim 9, wherein: In step (2), in the reverse water steam shift synthesis gas, n(H2-CO2) / n(CO+CO2) = 2.1-2.

5.

12. The method according to claim 11, wherein: In step (2), in the reverse water steam shift synthesis gas, n(H2-CO2) / n(CO+CO2) = 2.1-2.

3.

13. The method according to claim 9, wherein: In step (2), in the XRD spectrum of the reverse water gas shift catalyst, diffraction peaks of MgAl2O4 appear at 2θ of 19°, 37°, 45°, 60° and 66°.

14. The method according to claim 13, wherein: In step (2), the reverse water gas shift catalyst further contains a magnesium titanate phase.

15. The method according to claim 14, wherein: In step (2), in the XRD spectrum of the reverse water gas shift catalyst, diffraction peaks of MgTiO3 appear at 2θ of 21°, 24°, 33°, 35°, 49° and 53.5°; and / or The specific surface area of ​​the reverse water gas shift catalyst is 180-300 m 2 / g.

16. The method according to claim 15, wherein: The specific surface area of ​​the reverse water gas shift catalyst is 200-250m 2 / g.

17. The method according to claim 16, wherein: The method for preparing the reverse water gas shift catalyst comprises the following steps: (a) kneading an alumina binder, a magnesium-containing compound, a titanium-containing compound, a chromium-containing compound and water to obtain a mixture; (b) extruding the mixture, and performing a first drying and a first calcination to obtain a catalyst precursor A; (c) subjecting the catalyst precursor A to hydrothermal aging, and then subjecting it to a second drying and a second calcination to obtain a catalyst precursor B; (d) contacting the catalyst precursor B with a reducing gas containing hydrogen for a third time to obtain a reverse water gas shift catalyst; Wherein, the magnesium-containing compound is magnesium hydroxide, and the magnesium hydroxide is in the form of nanosheets with an average particle size of 100-500nm.

18. The method according to claim 17, wherein: In step (a), the alumina binder is selected from at least one of pseudo-boehmite, amorphous aluminum hydroxide and boehmite; And / or, the titanium-containing compound is at least one selected from metatitanic acid hydrate, metatitanic acid and nano titanium dioxide; And / or, the chromium-containing compound is selected from at least one of chromium nitrate, chromium acetate and chromium oxalate; And / or, in step (b), the first drying conditions include: temperature of 80-250°C; time of 1-25h; And / or, the first calcination conditions include: temperature of 300-700°C; time of 1-10h; And / or, in step (c), the hydrothermal aging conditions include: temperature of 100-200°C; time of 4-12h; And / or, the second drying conditions include: temperature of 80-150°C; time of 2-25h; And / or, the second calcination conditions include: temperature of 400-900°C; time of 1-10h; and / or, in step (d), the reducing gas containing hydrogen is a reformed synthetic gas; And / or, the conditions of the third contact include: temperature of 500-800°C; pressure of 1-5 MPa; volume space velocity of 5000-40000h -1 .

19. The method according to claim 18, wherein: In step (a), the alumina binder is pseudo-boehmite; And / or, the titanium-containing compound is metatitanic acid hydrate; And / or, the chromium-containing compound is chromium nitrate and / or chromium acetate; And / or, in step (b), the first drying conditions include: temperature of 100-200°C; time of 2-20h; And / or, the first calcination conditions include: temperature of 400-600°C; time of 3-8h; And / or, in step (c), the hydrothermal aging conditions include: temperature of 100-150°C; time of 6-10h; And / or, the second drying conditions include: temperature of 100-120°C; time of 2-20h; And / or, the second calcination conditions include: temperature of 500-800°C; time of 3-8h; And / or, the conditions of the third contact include: temperature of 600-700°C; pressure of 2-5 MPa; volume space velocity of 10000-20000h -1 .

20. The method according to any one of claims 1 to 4, wherein: In step (3), the synthesis gas feedstock contains hydrogen, carbon monoxide and carbon dioxide; And / or, the conditions of the methanol synthesis reaction include: reaction temperature of 200-300°C; pressure of 3-8MPa; volume space velocity of 5000-20000h -1 .

21. The method according to claim 20, wherein: In step (3), the conditions of the methanol synthesis reaction include: reaction temperature of 230-240°C; pressure of 4-6 MPa; volume space velocity of 8000-12000 h -1 .

22. The method according to claim 21, wherein: In step (3), in the synthesis gas raw material, n(H2-CO2) / n(CO+CO2) = 2.1-2.

5.

23. The method according to claim 22, wherein: In step (3), in the synthesis gas raw material, n(H2-CO2) / n(CO+CO2) = 2.1-2.

3.

24. The method according to any one of claims 1 to 4, wherein: The method further comprises the steps of purifying and desulfurizing the hydrocarbon-containing feedstock to obtain a hydrocarbon-containing stream; and / or The method further comprises separating water from the synthesis gas raw material before carrying out the methanol synthesis reaction, returning the separated water to step (1), and carrying out the methanol synthesis reaction on the obtained raw material; and / or The method further comprises distilling the synthetic material containing methanol to obtain a methanol product.

25. The method according to claim 24, wherein: The hydrocarbon-containing raw material is coke oven gas.

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