A method and system for producing olefins from coal

Abstract

The present disclosure relates to a method and system for producing olefins from coal, water enters a new energy water electrolysis hydrogen production device to prepare hydrogen and oxygen, which provides the required oxygen for the gasification reaction in the coal gasification device and the methanol-to-olefin catalyst regeneration, and provides the required hydrogen for the methanol synthesis reaction in the syngas-to-methanol device; and the carbon dioxide generated by the gasification reaction in the coal gasification device and the carbon dioxide separated from the flue gas of the methanol-to-olefin device are sent into a carbon dioxide electrolysis device to generate syngas and oxygen, the syngas is used as a raw material for preparing synthetic methanol, low-carbon olefins such as ethylene and propylene are produced through the methanol-to-olefin device, the water produced by the methanol-to-olefin device is further used as a raw material for electrolyzing water to produce hydrogen, and the oxygen is used as a feed for the gasification reaction and the methanol-to-olefin catalyst regeneration, thereby realizing the cyclic utilization of oxygen and the near-zero emission of carbon dioxide.

Description

Technical Field

[0001] This disclosure relates to the field of coal chemical technology, and more specifically, to a method and system for producing olefins from coal. Background Technology

[0002] Coal chemical engineering is the process of using coal as raw material and chemically processing it into gaseous, liquid, and solid energy sources and chemicals. The main route for producing low-carbon olefins from coal is coal-to-olefins (CTO). This route uses air separation to provide oxygen, which, along with coal-water slurry, enters a coal gasification reactor to produce crude syngas. The ratio of carbon monoxide to hydrogen in the crude syngas is insufficient for subsequent methanol synthesis. Therefore, the crude syngas needs to enter a shift converter to convert carbon monoxide into hydrogen and carbon dioxide. The shifted syngas is then sent to a syngas-to-methanol (STO) unit to produce methanol, which is then used in a STO unit to synthesize ethylene, propylene, and other low-carbon products. Because coal is a carbon-rich resource with relatively low hydrogen and oxygen content, obtaining syngas with a suitable carbon-to-hydrogen ratio requires the emission of large amounts of carbon dioxide during the shift conversion process.

[0003] In the existing coal-to-olefins (CTO) route, about 40% of the carbon in the raw coal is converted into low-carbon olefins, more than 50% of the carbon is converted into carbon dioxide and emitted, and less than half of the carbon is converted into low-carbon olefins, with a relatively large amount of carbon dioxide emissions.

[0004] CN101024783A discloses a chemical-power cogeneration method. In this method, crude syngas produced from carbon-rich feedstock is initially fed entirely into the chemical production process. Without undergoing a shift reaction to reduce the CO / H2 ratio, the syngas is cooled, purified, and directly used for chemical synthesis. After passing through the synthesis reactor, a portion of the syngas is converted into chemical products, while the unconverted syngas is either recycled back to the reactor for further reaction or used as fuel in a combined gas / steam cycle system for power generation. The primary purpose of this method is to utilize the waste heat from the syngas for energy conservation; however, it does not address the CO2 emission issue and cannot achieve ecological circular production.

[0005] CN114805023A discloses a zero-emission coal-to-olefins method. By introducing a reforming step, byproducts and CO2 generated during the production process are reformed, thereby achieving comprehensive utilization of CO2 produced during the coal-to-high-carbon (olefin) hydrocarbon process. The main purpose of this method is to efficiently utilize syngas and provide a zero-emission coal-to-olefins approach. However, the CO2 reforming introduced in this method is a strongly endothermic reaction, which leads to high carbon emissions. Summary of the Invention

[0006] The purpose of this disclosure is to provide a method and system for producing olefins from coal, which enables the recycling of oxygen, reduces carbon dioxide emissions during the coal-to-olefins process, and achieves green electricity consumption and clean utilization of coal.

[0007] To achieve the above objectives, this disclosure provides a method for producing olefins from coal, the method comprising the following steps:

[0008] S1. Water is introduced into the new energy water electrolysis hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained.

[0009] S2. Coal raw material, water, and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit for gasification reaction to obtain gasification products; the gasification products are separated to obtain coal gasification syngas and carbon dioxide;

[0010] S3. Water and carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to carry out a second electrolysis reaction to obtain electrolytic syngas and oxygen.

[0011] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol production unit to obtain synthetic methanol.

[0012] S5. The synthesized methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins.

[0013] At least a portion of the oxygen obtained in step S1 and / or step S3 is fed into the catalyst regeneration unit of the methanol-to-olefins unit to contact the methanol-to-olefins catalyst to restore catalyst activity and generate regenerated flue gas.

[0014] The carbon dioxide obtained from the separation of the regenerated flue gas is mixed with the carbon dioxide obtained in step S2 and then fed into the carbon dioxide electrolysis device to carry out the second electrolysis reaction.

[0015] Optionally, the method further includes: introducing at least a portion of the oxygen obtained in step S3 into a coal gasification device and mixing it with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction.

[0016] Optionally, in step S2, the weight ratio of the coal raw material, water, and oxygen is 1:(0.05-0.8):(0.5-1), preferably 1:(0.1-0.7):(0.6-0.9);

[0017] The coal gasification syngas includes carbon monoxide and hydrogen, and the molar ratio of carbon monoxide to hydrogen is 1:(0.2-1.2), preferably 1:(0.3-0.9);

[0018] The reaction conditions for the gasification reaction include: a reaction temperature of not less than 1000℃ and a reaction pressure of 1-9MPa;

[0019] Preferably, the reaction temperature is 1100-1400℃ and the reaction pressure is 5-8MPa.

[0020] Optionally, the water in steps S1 and S3 is desalinated water with a conductivity of 0.1-10 μs / cm and a pH of 5-9 at 25°C, preferably 6-8.

[0021] The electricity used for the first electrolysis reaction and the second electrolysis reaction comes from one or more of wind power, photovoltaic power, hydropower, nuclear power and biomass power generation;

[0022] Optionally, step S3 further includes introducing water and the carbon dioxide obtained in step S2 into a carbon dioxide electrolysis device to contact the electrolysis catalyst for a second electrolysis reaction, thereby obtaining electrolytic syngas and oxygen.

[0023] The electrolytic catalyst includes a nickel-based catalyst.

[0024] Optionally, the method further includes sending the gasification products into a purification device to separate carbon dioxide and remove impurities to obtain the coal gasification syngas; the impurities include at least one of ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide;

[0025] The electrolytic synthesis gas includes carbon monoxide and hydrogen, and the molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-5), preferably 1:(1-3).

[0026] Optionally, in step S4, the coal gasification syngas and electrolysis syngas are mixed with the hydrogen obtained in step S1 so that the molar ratio of carbon monoxide to hydrogen in the syngas to methanol device is 1:(2-3), preferably 1:(2-2.7).

[0027] The reaction product obtained in step S5 also includes water. Optionally, the method further includes: purifying the water in the reaction product obtained in step S5 to remove impurities from the water, and then allowing the purified water to enter the new energy water electrolysis hydrogen production device for the first electrolysis reaction; the impurities include at least one of aldehyde compounds, ketone compounds and metal ions.

[0028] The methanol-to-olefins catalyst includes a SAPO-34 molecular sieve catalyst.

[0029] The regenerated combustion aid used in the methanol-to-olefins catalyst is a mixture of regenerated flue gas and oxygen, wherein the oxygen content is 22-35% by volume, and the carbon content in the regenerated methanol-to-olefins catalyst is no more than 0.5 wt%.

[0030] On the other hand, this disclosure provides a system for producing olefins from coal, which includes a coal gasification unit, a syngas-to-methanol unit, a methanol-to-olefins unit, a new energy water electrolysis-to-hydrogen unit, and a carbon dioxide electrolysis unit.

[0031] The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet;

[0032] The syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet;

[0033] The methanol-to-olefins unit includes a methanol inlet, an olefins outlet, and a water outlet;

[0034] The new energy water electrolysis hydrogen production device includes a water inlet, an oxygen outlet, and a hydrogen outlet;

[0035] The carbon dioxide electrolysis device includes a carbon dioxide inlet, a water inlet, an electrolytic synthesis gas outlet, and an oxygen outlet;

[0036] The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device, and the hydrogen outlet of the new energy water electrolysis hydrogen production device is connected to the hydrogen inlet of the syngas to methanol device.

[0037] The water inlet of the carbon dioxide electrolysis device is used to connect to a water source;

[0038] The gasification product outlet of the coal gasification unit and the electrolytic synthesis gas outlet of the carbon dioxide electrolysis unit are respectively connected to the synthesis gas inlet of the synthesis gas to methanol unit, and the methanol outlet of the synthesis gas to methanol unit is connected to the methanol inlet of the methanol to olefins unit.

[0039] The methanol-to-olefins unit includes a catalyst regeneration unit, which includes an oxygen inlet and a regeneration flue gas outlet.

[0040] Optionally, the oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device and the oxygen inlet of the catalyst regeneration unit, respectively.

[0041] The regenerated flue gas outlet of the catalyst regeneration unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis device.

[0042] Optionally, the system also includes a water purification device;

[0043] Optionally, the water outlet of the methanol-to-olefins unit is connected to the water inlet of the new energy water electrolysis hydrogen production unit via a first pipeline, and the water purification device is installed on the first pipeline.

[0044] Optionally, the system further includes a purification device. Optionally, the gasification product outlet of the coal gasification device is connected to the syngas inlet of the syngas-to-methanol device via a second pipeline, and the purification device is installed on the second pipeline.

[0045] The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet.

[0046] The gasification product inlet of the purification device is connected to the gasification product outlet of the coal gasification device, the coal gasification syngas outlet of the purification device is connected to the syngas inlet of the syngas-to-methanol device, and the carbon dioxide outlet of the purification device is connected to the carbon dioxide inlet of the carbon dioxide electrolysis device.

[0047] Through the above technical solution, this disclosure provides a method and system for coal-to-olefins, which allows water to enter a new energy water electrolysis hydrogen production device to produce hydrogen and oxygen, providing the oxygen required for the gasification reaction in the coal gasification device and the regeneration of the methanol-to-olefins catalyst, and providing the hydrogen required for adjusting the carbon-hydrogen ratio of the syngas in the syngas-to-methanol device; and sending the carbon dioxide generated by the gasification reaction in the coal gasification device and the carbon dioxide generated by catalyst regeneration into a carbon dioxide electrolysis device to generate syngas and oxygen, using the syngas as a raw material for the synthesis of methanol, achieving near-zero carbon dioxide emissions; the water produced from the synthesis of olefins from methanol is further used as a raw material for water electrolysis hydrogen production, and the oxygen is again used as a raw material for the gasification reaction and the methanol-to-olefins reaction, thereby achieving the recycling of oxygen; the above-mentioned coal-to-olefins method and system provided by this disclosure can significantly reduce the scale of air separation units used in the prior art, eliminate the investment and construction of conversion units, and achieve green electricity consumption and clean utilization of coal.

[0048] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0049] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0050] Figure 1 This is a process flow diagram of coal-to-olefins production used in Embodiment 1 of this disclosure.

[0051] Figure 2 This is a process flow diagram of coal-to-olefins production used in Comparative Example 1 of this disclosure. Detailed Implementation

[0052] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0053] In this disclosure, directional terms such as "up" and "down" refer to the up and down in the normal operating state of the device, while "inside" and "outside" refer to the outline of the device itself.

[0054] In this disclosure, olefins refer to low-carbon olefins such as ethylene and propylene.

[0055] The first aspect of this disclosure provides a method for producing olefins from coal, the method comprising the following steps:

[0056] S1. Water is introduced into the new energy water electrolysis hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained.

[0057] S2. Coal raw material, water, and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit for gasification reaction to obtain gasification products; the gasification products are separated to obtain coal gasification syngas and carbon dioxide;

[0058] S3. Water and carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to carry out a second electrolysis reaction to obtain electrolytic syngas and oxygen.

[0059] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol production unit to obtain synthetic methanol.

[0060] S5. The synthesized methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins.

[0061] At least a portion of the oxygen obtained in step S1 and / or step S3 is fed into the catalyst regeneration unit of the methanol-to-olefins (MTO) unit to contact the MTO catalyst in order to restore the activity of the MTO catalyst and generate regenerated flue gas.

[0062] The carbon dioxide obtained from the separation of the regenerated flue gas is mixed with the carbon dioxide obtained in step S2 and then fed into the carbon dioxide electrolysis device to carry out the second electrolysis reaction.

[0063] In this disclosure, the reaction conditions for the first and second electrolysis reactions are not particularly limited and can be selected as needed.

[0064] In the method provided in this disclosure, water is fed into a new energy water electrolysis hydrogen production device to produce green hydrogen and green oxygen. The produced green oxygen provides the oxygen required for the gasification reaction in the coal gasification device and the catalyst regeneration in the methanol production system. The produced green hydrogen provides the hydrogen required for the methanol production reaction in the syngas to methanol device. Furthermore, the carbon dioxide generated from the gasification reaction in the coal gasification device and the carbon dioxide obtained from the catalyst regeneration flue gas are fed into a carbon dioxide electrolysis device to produce syngas and oxygen. The syngas is used as a raw material for the production of synthetic methanol. The water produced from the synthesis of olefins from methanol is further used as a raw material for the new energy water electrolysis hydrogen production. The oxygen is again used as a feed for the gasification reaction and the catalyst regeneration in the methanol to olefins production process, thereby achieving the recycling of oxygen and near-zero carbon dioxide emissions.

[0065] According to one embodiment of this disclosure, the method further includes: introducing at least a portion of the oxygen obtained in step S3 into a coal gasification device and mixing it with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction;

[0066] Optionally, the gasification reaction can be either coal-water slurry gasification or pulverized dry coal gasification.

[0067] According to one embodiment of this disclosure, in step S2, the weight ratio of the coal raw material, water and oxygen is 1:(0.05-0.8):(0.5-1), preferably 1:(0.1-0.7):(0.6-0.9); the coal gasification syngas includes carbon monoxide and hydrogen, and optionally, the molar ratio of carbon monoxide to hydrogen is 1:(0.2-1.2), preferably 1:(0.3-0.9).

[0068] According to one embodiment of this disclosure, the water in steps S1 and S3 is desalinated water with a conductivity of 0.1-10 μs / cm and a pH value of 5-9 at 25°C, preferably 6-8.

[0069] The electricity used for the first electrolysis reaction and the second electrolysis reaction comes from one or more of wind power, photovoltaic power, hydropower, nuclear power and biomass power generation;

[0070] Optionally, step S3 further includes introducing water and the carbon dioxide obtained in step S2 into a carbon dioxide electrolysis device to contact the electrolysis catalyst for a second electrolysis reaction, thereby obtaining electrolytic syngas and oxygen.

[0071] The electrolysis catalyst includes a nickel-based catalyst;

[0072] In step S2, the reaction conditions for the gasification reaction include: a reaction temperature of not less than 1000℃ and a reaction pressure of 1-9MPa;

[0073] Preferably, the reaction temperature is 1100-1400℃ and the reaction pressure is 5-8MPa.

[0074] According to one embodiment of this disclosure, the method further includes: sending the gasification product into a purification device to separate carbon dioxide and remove impurities to obtain the coal gasification syngas; the impurities include at least one of ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide.

[0075] The electrolytic synthesis gas includes carbon monoxide and hydrogen; optionally, the molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-5), preferably 1:(1-3).

[0076] According to one embodiment of this disclosure, in step S4, the coal gasification syngas and electrolysis syngas are mixed with the hydrogen obtained in step S1, so that the molar ratio of carbon monoxide to hydrogen in the syngas-to-methanol device is 1:(2-3), preferably 1:(2-2.7).

[0077] The reaction product obtained in step S5 also includes water. Optionally, the method further includes: purifying the water in the reaction product obtained in step S5 to remove impurities in the water, and then allowing the purified water to enter the new energy water electrolysis hydrogen production device for the first electrolysis reaction; the impurities include at least one of aldehyde compounds, ketone compounds and metal ions.

[0078] The methanol-to-olefins catalyst includes a SAPO-34 molecular sieve catalyst.

[0079] The regenerated combustion aid used in the methanol-to-olefins catalyst is a mixture of regenerated flue gas and oxygen, wherein the oxygen content is 22-35% by volume; the carbon content in the regenerated methanol-to-olefins catalyst is no more than 0.5 wt%.

[0080] The second aspect of this disclosure provides a system for producing olefins from coal, the system comprising a coal gasification unit, a methanol-to-olefins unit, a new energy water electrolysis hydrogen production unit, and a carbon dioxide electrolysis unit;

[0081] The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet;

[0082] The syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet;

[0083] The methanol-to-olefins unit includes a methanol inlet, an olefins outlet, and a water outlet;

[0084] The new energy water electrolysis hydrogen production device includes a water inlet, an oxygen outlet, and a hydrogen outlet;

[0085] The carbon dioxide electrolysis device includes a carbon dioxide inlet, a water inlet, an electrolytic synthesis gas outlet, and an oxygen outlet;

[0086] The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device, and the hydrogen outlet of the new energy water electrolysis hydrogen production device is connected to the hydrogen inlet of the syngas to methanol device.

[0087] The water inlet of the carbon dioxide electrolysis device is used to connect to a water source;

[0088] The gasification product outlet of the coal gasification unit and the electrolytic synthesis gas outlet of the carbon dioxide electrolysis unit are respectively connected to the synthesis gas inlet of the synthesis gas to methanol unit, and the methanol outlet of the synthesis gas to methanol unit is connected to the methanol inlet of the methanol to olefins unit.

[0089] The methanol-to-olefins unit includes a catalyst regeneration unit, which includes an oxygen inlet and a regeneration flue gas outlet.

[0090] Optionally, the oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device and the oxygen inlet of the catalyst regeneration unit, respectively.

[0091] The regenerated flue gas outlet of the catalyst regeneration unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis device.

[0092] According to one embodiment of this disclosure, the system further includes a water purification device;

[0093] Optionally, the water outlet of the methanol-to-olefins unit is connected to the water inlet of the new energy water electrolysis hydrogen production unit via a first pipeline, and the water purification device is installed on the first pipeline.

[0094] According to this disclosure, the system further includes a purification device. Optionally, the gasification product outlet of the coal gasification device is connected to the syngas inlet of the syngas-to-methanol device via a second pipeline, and the purification device is installed on the second pipeline.

[0095] The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet.

[0096] The gasification product outlet of the coal gasification unit is connected to the gasification product inlet of the purification unit, the coal gasification syngas outlet of the purification unit is connected to the syngas inlet of the syngas-to-methanol unit, and the carbon dioxide outlet of the purification unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis unit.

[0097] like Figure 1As shown, in one exemplary embodiment of the coal-to-olefins system provided in this disclosure, the system includes:

[0098] Coal gasification units, syngas-to-methanol units, methanol-to-olefins units, new energy water electrolysis-to-hydrogen units, and carbon dioxide electrolysis units;

[0099] The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet; the syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet; the methanol-to-olefins unit includes a methanol inlet, an olefin outlet, and a water outlet; the new energy water electrolysis hydrogen production unit includes a water inlet, an oxygen outlet, and a hydrogen outlet; the carbon dioxide electrolysis unit includes a carbon dioxide inlet, a water inlet, an electrolytic syngas outlet, and an oxygen outlet; the oxygen outlet of the new energy water electrolysis hydrogen production unit is connected to the oxygen inlet of the coal gasification unit, and the hydrogen outlet of the new energy water electrolysis hydrogen production unit is connected to the hydrogen inlet of the syngas-to-methanol unit; the water inlet of the carbon dioxide electrolysis unit is used to connect to a water source; the electrolytic syngas outlet of the carbon dioxide electrolysis unit... The system includes a purification device. The gasification product outlet of the coal gasification unit is connected to the syngas inlet of the syngas-to-methanol unit, and the methanol outlet of the syngas-to-methanol unit is connected to the methanol inlet of the methanol-to-olefins unit. The purification device is installed on the second pipeline. The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet. The gasification product inlet of the purification device is connected to the gasification product outlet of the coal gasification unit, the coal gasification syngas outlet of the purification device is connected to the syngas inlet of the syngas-to-methanol unit, and the carbon dioxide outlet of the purification device is connected to the carbon dioxide inlet of the carbon dioxide electrolysis unit.

[0100] The methanol-to-olefins unit includes a catalyst regeneration unit, which includes an oxygen inlet and a regeneration flue gas outlet.

[0101] The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device and the oxygen inlet of the catalyst regeneration unit, respectively; the regeneration flue gas outlet of the catalyst regeneration unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis device; the system also includes a water purification device; the water outlet of the methanol to olefins device is connected to the water inlet of the new energy water electrolysis hydrogen production device via a first pipeline, and the water purification device is installed on the first pipeline.

[0102] use Figure 1 The system shown is a method for producing olefins from coal, and the specific process includes:

[0103] S1. After desalination, water enters the new energy electrolysis water hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained.

[0104] S2. Coal raw material, water and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification device to carry out a gasification reaction to obtain gasification products; the gasification products are sent to a purification device for separation to obtain coal gasification syngas and carbon dioxide, and to remove ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds and cyanide impurities from the gasification products.

[0105] S3. The desalinated water and the carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to contact the nickel-based catalyst for a second electrolysis reaction, yielding electrolytic syngas and oxygen; the electrolytic syngas includes carbon monoxide and hydrogen.

[0106] At least a portion of the oxygen obtained from the second electrolysis reaction is introduced into a coal gasification unit and mixed with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction;

[0107] The oxygen obtained in step S1 and step S3 is fed into the catalyst regeneration unit of the methanol-to-olefins unit to contact the methanol-to-olefins catalyst to restore its activity and generate regenerated flue gas.

[0108] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol unit to obtain synthetic methanol.

[0109] S5. The synthetic methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins. The reaction product also includes water. The obtained water is purified to remove aldehydes, ketones and metal ions. The purified water is then fed into the new energy water electrolysis hydrogen production unit for the first electrolysis reaction.

[0110] The regenerated combustion aid used in this methanol-to-olefins catalyst is a mixture of regenerated flue gas and oxygen, with an oxygen content of 22-35% by volume; the carbon content in the regenerated methanol-to-olefins catalyst is no more than 0.5 wt%.

[0111] The carbon dioxide in the regenerated flue gas is mixed with the carbon dioxide obtained in step S2 and then fed into the carbon dioxide electrolysis device to continue the second electrolysis reaction.

[0112] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0113] Example 1

[0114] The process described in this embodiment is as follows: Figure 1The new energy water electrolysis hydrogen production unit and carbon dioxide electrocatalytic unit are driven by wind power and photovoltaic power; the coal raw material is bituminous coal from a certain region, with a coal raw material consumption of 1.23 million tons / year, and its composition is detailed in Table 1.

[0115] Table 1. Composition Analysis of Raw Coal

[0116]

[0117] use Figure 1 The experimental procedure for using the system shown to produce olefins from coal is as follows:

[0118] S1. The desalinated water is fed into the new energy electrolysis water hydrogen production device for the first electrolysis reaction to obtain hydrogen and oxygen; the conductivity of the desalinated water is 9 μs / cm and the pH value is 7 at 25℃.

[0119] S2. Coal raw material, water and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit to carry out a coal-water slurry gasification reaction to obtain gasification products; the weight ratio of coal raw material, water and oxygen is 1:0.33:0.75; the gasification temperature is 1300℃ and the gasification pressure is 6.5MPa.

[0120] The gasification products are sent to a purification device to remove impurities such as ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide. After separation, coal gasification syngas and carbon dioxide are obtained. The molar ratio of hydrogen to carbon monoxide in the coal gasification syngas is 0.83:1.

[0121] S3. The desalinated water and the carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to contact a nickel-based catalyst for a second electrolysis reaction, yielding electrolytic syngas and oxygen. The electrolytic syngas includes carbon monoxide and hydrogen. The desalinated water has a conductivity of 9 μS / cm and a pH of 7 at 25°C. The reaction temperature of the second electrolysis reaction is 60°C, the reaction pressure is atmospheric pressure, and the molar ratio of hydrogen to carbon monoxide in the electrolytic syngas is 2:1.

[0122] At least a portion of the oxygen obtained from the second electrolysis reaction is introduced into a coal gasification device and mixed with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction under the same conditions as the gasification reaction in step S2.

[0123] S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol unit to obtain synthetic methanol.

[0124] The electrolytic syngas and coal gasification syngas are mixed with the hydrogen obtained in step S1 to make the molar ratio of carbon monoxide to hydrogen in the syngas to methanol unit 1:2.2.

[0125] S5. The synthesized methanol is introduced into the methanol-to-olefins unit and reacted with the methanol-to-olefins catalyst to obtain ethylene, propylene and water; the water is desalted and then recycled in the system.

[0126] The oxygen obtained from another part of step S1 and the oxygen obtained from step S3 are fed into the catalyst regeneration unit of the methanol-to-olefins unit to contact the methanol-to-olefins catalyst to restore the activity of the methanol-to-olefins catalyst and generate regenerated flue gas.

[0127] The carbon dioxide in the regenerated flue gas is mixed with the carbon dioxide obtained in step S2 and then fed into the carbon dioxide electrolysis device to continue the second electrolysis reaction.

[0128] The methanol-to-olefins catalyst is a SAPO-34 catalyst; the regeneration combustion aid for the methanol-to-olefins catalyst is a mixture of regenerated flue gas and oxygen, wherein the oxygen content is 30% by volume, and the carbon content in the regenerated methanol-to-olefins catalyst is 0.4 wt%.

[0129] The products and their indicators obtained in this embodiment are shown in Table 2.

[0130] Comparative Example 1

[0131] For the comparative process flow, please refer to [link / reference]. Figure 2 An air separation unit and a conversion unit are installed in the coal-to-olefins system; the coal raw material consumption is 3 million tons / year, and the composition of the raw coal is the same as in Example 1, as shown in Table 1.

[0132] Air is sent to an air separation unit to separate oxygen and nitrogen. The coal feedstock and the oxygen separated from the air separation unit are then sent to a coal gasification unit. Coal gasification uses a coal-water slurry gasification method, with an oxygen-to-coal mass ratio of 0.75:1, a gasification temperature of 1300℃, and a gasification pressure of 6.5 MPa. Gasification products include carbon monoxide, hydrogen, and carbon dioxide. A portion of the carbon monoxide from the gasification products is sent to a shift converter for carbon monoxide conversion, transforming water and carbon monoxide into carbon dioxide and hydrogen. The converted products are mixed with the non-shifted gases to achieve a hydrogen-to-carbon monoxide molar ratio of 2.2:1. The mixed gas then passes through a purification unit to separate carbon dioxide and syngas.

[0133] Syngas is sent to a syngas-to-methanol unit to synthesize methanol. The resulting methanol is then sent to a methanol-to-olefins unit where it is catalytically reacted with a fluidized bed catalyst to produce water, ethylene, and propylene.

[0134] The products and their indicators obtained in Comparative Example 1 are shown in Table 2.

[0135] Table 2. Products and their properties prepared in Example 1 and Comparative Example 1.

[0136] Serial Number project Example 1 Comparative Example 1 1 Total raw coal volume, 10,000 tons / year 119 300 2 Ethylene products, 10,000 tons / year 35.4 35.4 3 Propylene products, 10,000 tons / year 28.8 28.8 4 Total carbon emissions, 10,000 tons / year 246 683 5 Process carbon emissions, 10,000 tons / year 9 402

[0137] Example 2

[0138] The raw coal used in Example 2 was gas coal from a certain region, and its composition is shown in Table 3.

[0139] Table 3. Composition Analysis of Raw Coal

[0140]

[0141] The process flow in this embodiment is the same as that in embodiment 1, except that the coal gasification device uses a dry coal powder gasification method.

[0142] In this embodiment, the weight ratio of raw coal, water, and oxygen in the feed to the coal gasification unit is 1:0.1:0.78, the gasification temperature is 1400℃, the gasification pressure is 4.0MPa, and the molar ratio of hydrogen to carbon monoxide in the generated syngas is 0.35.

[0143] The products and their indicators obtained in Example 2 are shown in Table 4.

[0144] Comparative Example 2

[0145] The process flow of Comparative Example 2 is the same as that of Comparative Example 1, except that the coal gasification unit uses a dry coal powder gasification method, and the coal raw material consumption is 2.61 million tons / year. The composition of the raw coal is the same as that of Example 2, as shown in Table 3.

[0146] The products and their indicators obtained in Comparative Example 2 are shown in Table 4.

[0147] Table 4. Products and their indicators prepared in Example 2 and Comparative Example 2.

[0148]

[0149]

[0150] As can be seen from Tables 2 and 4, under the condition of the same ethylene and propylene production, the raw coal consumption of Example 1 is 1.19 million tons / year, the raw coal consumption of Example 2 is 1.01 million tons / year, the raw coal consumption of Comparative Example 1 is 3 million tons / year, and the raw coal consumption of Comparative Example 2 is 2.61 million tons / year. It can be seen that, under the condition of the same olefin production, the raw coal consumption of Examples 1 and 2 is significantly reduced compared with Comparative Examples 1 and 2. Furthermore, the total carbon emissions of Example 1 are reduced by 4.37 million tons / year compared with Comparative Example 1, and the total carbon emissions of Example 2 are reduced by 4.19 million tons / year compared with Comparative Example 2.

[0151] As can be seen, in the process flow disclosed herein, the water electrolysis and carbon dioxide electrocatalytic devices use green electricity resources such as wind power and hydropower, and all the oxygen in the coal gasification device is generated in the system, which greatly reduces the scale of the air separation unit. Furthermore, the water generated in the carbon dioxide and methanol-to-olefins process is recycled through the above devices, which further realizes the recycling of oxygen and reduces the carbon emissions of the entire production process.

[0152] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0153] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0154] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for producing olefins from coal, characterized in that, The method includes the following steps: S1. Water is introduced into the new energy water electrolysis hydrogen production device to carry out the first electrolysis reaction, and hydrogen and oxygen are obtained. S2. Coal raw material, water, and at least a portion of the oxygen obtained in step S1 are fed into a coal gasification unit for gasification reaction to obtain gasification products; the gasification products are separated to obtain coal gasification syngas and carbon dioxide; S3. Water and carbon dioxide obtained in step S2 are fed into a carbon dioxide electrolysis device to carry out a second electrolysis reaction to obtain electrolytic syngas and oxygen. S4. The coal gasification syngas, electrolysis syngas and hydrogen obtained in step S1 are fed into the syngas to methanol production unit to obtain synthetic methanol. S5. The synthesized methanol is reacted with the methanol-to-olefins catalyst to obtain a reaction product containing olefins. At least a portion of the oxygen obtained in step S1 and / or step S3 is fed into the catalyst regeneration unit of the methanol-to-olefins (MTO) unit to contact the MTO catalyst in order to restore the activity of the MTO catalyst and generate regenerated flue gas. The carbon dioxide obtained from the separation of the regenerated flue gas is mixed with the carbon dioxide obtained in step S2 and then fed into the carbon dioxide electrolysis device to carry out the second electrolysis reaction. The reaction product obtained in step S5 also includes water. The method further includes: purifying the water obtained in step S5 to remove impurities from the water, and then allowing the purified water to enter the new energy water electrolysis hydrogen production device for the first electrolysis reaction. The electrolytic synthesis gas includes carbon monoxide and hydrogen. The molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-5). The regenerated combustion aid used in the methanol-to-olefins catalyst is a mixture of regenerated flue gas and oxygen, wherein the oxygen content is 22-35% by volume.

2. The method according to claim 1, wherein, The method further includes: introducing at least a portion of the oxygen obtained in step S3 into a coal gasification device and mixing it with the coal raw material, water, and at least a portion of the oxygen obtained in step S1 to carry out a gasification reaction.

3. The method according to claim 1, wherein, In step S2, the weight ratio of the coal raw material, water and oxygen is 1:(0.05-0.8):(0.5-1); the coal gasification syngas includes carbon monoxide and hydrogen, and the molar ratio of carbon monoxide to hydrogen is 1:(0.2-1.2).

4. The method according to claim 3, wherein, In step S2, the weight ratio of the coal raw material, water and oxygen is 1:(0.1-0.7):(0.6-0.9); the molar ratio of carbon monoxide to hydrogen is 1:(0.3-0.9).

5. The method according to claim 1, wherein, The water in steps S1 and S3 is desalinated water with a conductivity of 0.1-10 μs / cm and a pH of 5-9 at 25°C. The electricity used for the first electrolysis reaction and the second electrolysis reaction comes from one or more of wind power, photovoltaic power, hydropower, nuclear power and biomass power generation; Step S3 also includes introducing water and the carbon dioxide obtained in step S2 into a carbon dioxide electrolysis device to contact the electrolysis catalyst for a second electrolysis reaction, thereby obtaining electrolytic syngas and oxygen. The electrolysis catalyst includes a nickel-based catalyst; In step S2, the reaction conditions for the gasification reaction include: a reaction temperature of not less than 1000℃ and a reaction pressure of 1-9MPa.

6. The method according to claim 5, wherein, The water used in steps S1 and S3 has a pH of 6-8 at 25°C. In step S2, the reaction conditions for the gasification reaction include: a reaction temperature of 1100-1400℃ and a reaction pressure of 5-8MPa.

7. The method according to claim 1, wherein, The method further includes: sending the gasification products into a purification device to separate carbon dioxide and remove impurities to obtain the coal gasification syngas; the impurities include at least one of ammonia, mercury, hydrogen sulfide, carbonyl sulfide, oxygen-containing compounds, and cyanide.

8. The method according to claim 1, wherein, The molar ratio of carbon monoxide to hydrogen in the electrolytic synthesis gas is 1:(1-3).

9. The method according to claim 1, wherein, In step S4, the coal gasification syngas and electrolysis syngas are mixed with the hydrogen obtained in step S1 so that the molar ratio of carbon monoxide to hydrogen in the syngas to methanol device is 1:(2-3). The impurities include at least one of aldehydes, ketones, and metal ions.

10. The method according to claim 9, wherein, The molar ratio of carbon monoxide to hydrogen in the syngas-to-methanol unit is 1:(2-2.7).

11. The method according to claim 1, wherein, The methanol-to-olefins catalyst includes a SAPO-34 molecular sieve catalyst. The carbon content in the regenerated methanol-to-olefins catalyst is no more than 0.5 wt%.

12. A system for producing olefins from coal, characterized in that, The system includes a coal gasification unit, a syngas-to-methanol unit, a methanol-to-olefins unit, a new energy water electrolysis-to-hydrogen unit, and a carbon dioxide electrolysis unit. The coal gasification unit includes a raw coal inlet, a water inlet, an oxygen inlet, and a gasification product outlet; The syngas-to-methanol unit includes a syngas inlet, a hydrogen inlet, and a methanol outlet; The methanol-to-olefins unit includes a methanol inlet, an olefins outlet, and a water outlet; The new energy water electrolysis hydrogen production device includes a water inlet, an oxygen outlet, and a hydrogen outlet; The carbon dioxide electrolysis device includes a carbon dioxide inlet, a water inlet, an electrolytic synthesis gas outlet, and an oxygen outlet; The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device, and the hydrogen outlet of the new energy water electrolysis hydrogen production device is connected to the hydrogen inlet of the syngas to methanol device. The water inlet of the carbon dioxide electrolysis device is used to connect to a water source; The gasification product outlet of the coal gasification unit and the electrolytic synthesis gas outlet of the carbon dioxide electrolysis unit are respectively connected to the synthesis gas inlet of the synthesis gas to methanol unit, and the methanol outlet of the synthesis gas to methanol unit is connected to the methanol inlet of the methanol to olefins unit. The methanol-to-olefins unit includes a catalyst regeneration unit, which includes an oxygen inlet and a regeneration flue gas outlet. The oxygen outlet of the new energy water electrolysis hydrogen production device is connected to the oxygen inlet of the coal gasification device and the oxygen inlet of the catalyst regeneration unit, respectively. The regeneration flue gas outlet of the catalyst regeneration unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis device. The system also includes a water purification device; The water outlet of the methanol-to-olefins unit is connected to the water inlet of the new energy water electrolysis hydrogen production unit via a first pipeline, and the water purification device is installed on the first pipeline.

13. The system according to claim 12, wherein, The system also includes a purification device. The gasification product outlet of the coal gasification device is connected to the syngas inlet of the syngas to methanol device via a second pipeline. The purification device is installed on the second pipeline. The purification device includes a gasification product inlet, a carbon dioxide outlet, and a coal gasification syngas outlet. The gasification product outlet of the coal gasification unit is connected to the gasification product inlet of the purification unit, the coal gasification syngas outlet of the purification unit is connected to the syngas inlet of the syngas-to-methanol unit, and the carbon dioxide outlet of the purification unit is connected to the carbon dioxide inlet of the carbon dioxide electrolysis unit.

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