Process for the production of syngas and high concentration co from coal char powder chemical looping gasification

Abstract

This invention relates to the field of solid waste resource utilization technology, and discloses a method for preparing syngas and high-concentration CO by chemical chain gasification of coal coke powder. The method includes the following steps: (1) chemical chain gasification reaction of coal coke powder, a disposable catalyst and an oxygen carrier, followed by gas-solid separation to obtain syngas and a first solid product; (2) reaction of the first solid product under a CO2 atmosphere and at 700-1000℃, followed by gas-solid separation to obtain a second solid product and a gaseous product with a CO concentration ≥80% by volume; wherein, the disposable catalyst is alkali lignin. The method for preparing syngas and co-producing high-concentration CO by chemical chain gasification of coal coke powder with a disposable catalyst adopted in this invention solves the shortcomings of traditional coal coke powder utilization processes, such as high tar content, low gasification efficiency and difficulty in controlling the H / C ratio, and breaks through the bottleneck of alkali metal utilization in the utilization of alkali lignin. It is of great significance for the co-resource utilization of industrial organic waste.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, specifically to a method for preparing syngas and high-concentration CO by chemical loop gasification of coal coke powder. Background Technology

[0002] Chinese patent application CN201810865353.6 discloses a method for utilizing waste heat from coal coke powder in a fluidized bed. The method involves cooling the high-temperature dry distilled coal coke powder to a safe packaging temperature and utilizing the waste heat to generate steam during this process. A multi-stage series connection is used to classify the coal coke powder by temperature level, dividing it into a high-temperature steam generation zone and a medium preheating section. The high-temperature coal coke powder first flows through the steam generation zone to generate steam, then flows through the cooling medium preheating zone for cooling, and finally flows out. This utilizes the waste heat of the coal coke powder to improve energy efficiency. Chinese patent application CN201410803453.8 discloses a method for preparing active coal coke powder for solid oxide fuel cells. This method involves mechanically grinding 20-50 mesh industrial coal coke particles for 30-120 hours, then thoroughly mixing the ground coal coke particles with a nitrate composite catalyst. The resulting active coal coke powder exhibits high reactivity and can significantly improve the output performance of direct carbon solid oxide fuel cells.

[0003] The aforementioned patents relate to the utilization of waste heat from coal coke powder and the preparation of activated coal coke powder, but do not address the chemical looping gasification of coal coke powder to produce high-quality syngas coupled with the co-production of carbon monoxide (CO). Furthermore, conventional coal coke powder gasification processes suffer from reaction kinetic bottlenecks, requiring conversion under relatively harsh conditions, resulting in low conversion rates. Additionally, this gasification process requires oxygen-enriched media such as water vapor, making operation cumbersome and costly. Moreover, air gasification faces the problem of nitrogen dilution, hindering the achievement of efficient conversion. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide a method for preparing syngas and high-concentration CO by chemical looping gasification of coal coke powder. This method uses alkali lignin, a by-product of the papermaking industry, as a disposable catalyst and coal coke powder, a by-product of the coal coking industry, as the raw material for chemical looping gasification to prepare syngas and high-concentration CO, realizing the resource utilization of solid waste with high conversion efficiency.

[0005] To achieve the above objectives, the present invention provides a method for preparing syngas and high-concentration CO by chemical looping gasification of coal coke powder, the method comprising the following steps:

[0006] (1) Coal coke powder, disposable catalyst and oxygen carrier are subjected to chemical chain gasification reaction, and the products of the chemical chain gasification are subjected to gas-solid separation to obtain syngas and first solid product;

[0007] (2) The first solid product is reacted in a CO2 atmosphere at 700-1000°C. The reaction product is then subjected to gas-solid separation to obtain a second solid product and a gaseous product with a CO concentration ≥80% by volume.

[0008] The disposable catalyst is alkali lignin.

[0009] Preferably, in step (1), the water content of the alkali lignin is 15-20 wt%, and the particle size is 90-150 mesh;

[0010] Preferably, in step (1), the water content of the coal coke powder is 15-20 wt%, and the particle size is 90-150 mesh.

[0011] Preferably, in step (1), the oxygen carrier is selected from one or more of Fe-based, Ni-based, Cu-based, and Mn-based materials;

[0012] Preferably, in step (1), the oxygen carrier comprises one or more of the following: spinel structure, core-shell structure, and helical structure;

[0013] Preferably, in step (1), the particle size of the oxygen carrier is 0.15 to 0.4 mm.

[0014] Preferably, in the method according to claim 1 or 3, the oxygen carrier in step (1) is Fe2O3@Sr3Fe2O 7-x -Ca 0.5 Mn 0.5 O composite oxygen carrier and / or CuO@Sr3Fe2O 7-x -Ca 0.5 Mn 0.5 O-composite oxygen carrier;

[0015] Preferably, the composite oxygen carrier is prepared by the sol-gel method.

[0016] Preferably, in step (1), the weight ratio of the coal coke powder, the disposable catalyst and the oxygen carrier is 0.5-1.5:1:0.5-1.5.

[0017] Preferably, in step (1), the conditions for the chemical chain gasification reaction include: a temperature of 700–1000°C and a time of 30–60 min.

[0018] Preferably, in step (1), the synthesis gas contains H2 and CO, and the molar ratio of H2 to CO is 1.5 to 2.0.

[0019] Preferably, in step (2), the reaction time is 30 to 60 minutes.

[0020] Preferably, the method further includes: calcining the second solid product obtained in step (2) at 700-1000°C, and then returning it to step (1) for reuse as an oxygen carrier.

[0021] Preferably, the calcination time is 60 to 120 minutes.

[0022] Compared with the prior art, the method described in this invention has the following advantages:

[0023] 1. The method provided by the present invention achieves chemical looping gasification by using an oxygen carrier to provide lattice oxygen during the gasification process, thus avoiding the oxygen preparation process in the traditional gasification process; and alkali lignin, as a disposable catalyst, catalyzes the cracking of tar during the reaction process, thereby improving the reaction efficiency.

[0024] 2. The method provided by this invention achieves the staged conversion and utilization of CO2 while generating high-concentration CO, through the oxidation reaction of CO2 with a reducing oxygen carrier and the cracking reaction of CO2 with the semi-coke produced in the chemical looping gasification stage, thus realizing the resource utilization of the greenhouse gas CO2. In addition, the alkali metal elements provided by alkali lignin have a catalytic effect on the CO2 cracking reaction, further improving the resource utilization efficiency of alkali lignin.

[0025] 3. The method for producing high-concentration CO by chemical looping gasification of coal coke powder with a discardable catalyst, which is adopted in this invention, solves the shortcomings of traditional coal coke powder utilization, such as high tar content, low gasification efficiency, and difficulty in controlling the H / C ratio. It also breaks through the bottleneck of alkali metal utilization in the utilization of alkali lignin, which is of great significance for the co-resource utilization of industrial organic waste. Attached Figure Description

[0026] Figure 1 This is a partial process flow diagram of an embodiment of the method for preparing syngas and high-concentration CO by chemical chain gasification of coal coke powder provided by the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention 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 the present invention.

[0028] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] This invention provides a method for preparing syngas and high-concentration CO by chemical looping gasification of coal coke powder. Please refer to the following reference. Figure 1 The method includes the following steps:

[0030] (1) Coal coke powder, disposable catalyst and oxygen carrier are subjected to chemical chain gasification reaction, and the products of the chemical chain gasification are subjected to gas-solid separation to obtain syngas and first solid product;

[0031] (2) The first solid product is reacted in a CO2 atmosphere at 700-1000°C. The reaction product is then subjected to gas-solid separation to obtain a second solid product and a gaseous product with a CO concentration ≥80% by volume.

[0032] The disposable catalyst is alkali lignin.

[0033] In the method described in this invention, in the chemical chain gasification reaction carried out in step (1), the lattice oxygen provided by the oxygen carrier partially oxidizes the coal coke powder and alkali lignin to produce high-quality syngas and high-concentration CO. At the same time, alkali metals such as K and Na in alkali lignin will enhance the transfer of lattice oxygen in the oxygen carrier and catalyze the oxidation reaction of the organic matter in the coal coke powder and alkali lignin. Then, the reaction products are separated into syngas and a first solid product. The first solid product contains a reduced oxygen carrier (i.e., a reduced oxygen carrier) and half coke produced in the chemical chain gasification stage. The syngas contains H2, CO, CO2 and CH4. In step (2), through the oxidation reaction of CO2 with the reduced oxygen carrier and the cracking reaction of CO2 with half coke, a second solid product and a gaseous product with a CO concentration ≥ 80% by volume (i.e., high-concentration CO) are generated. The second solid product contains a reduced oxygen carrier a.

[0034] Alkali lignin is a byproduct of the papermaking industry. The presence of alkali metals in alkali lignin limits its application; improper use not only wastes resources but also poses environmental risks. However, in the method described in this invention, alkali lignin is used as a disposable catalyst, with coal coke powder as the feedstock for chemical looping gasification. In this chemical looping gasification reaction, lattice oxygen provided by the oxygen carrier partially oxidizes the coal coke powder and alkali lignin to produce high-quality syngas. Simultaneously, alkali metals such as K and Na in alkali lignin enhance the transfer of lattice oxygen in the oxygen carrier and catalyze the oxidation of the organic components in the coal coke powder and alkali lignin. Therefore, the method provided by this invention not only overcomes the bottleneck of alkali metal utilization in the process of alkali lignin utilization, realizing the resource utilization of alkali lignin, but also improves the conversion efficiency of the chemical looping gasification reaction.

[0035] The present invention does not limit the specific parameters of the alkali lignin, and can be any alkali lignin commonly used in the art. In order to facilitate the chemical looping gasification reaction, in a preferred embodiment, in step (1), the water content of the alkali lignin is 15-20 wt%, and the particle size is 90-150 mesh. The fine particle properties of alkali lignin are conducive to sufficient contact of the oxygen carrier and improve the heat / mass transfer efficiency.

[0036] In a specific embodiment, the alkali lignin is obtained by pretreatment of conventional alkali lignin. More specifically, the pretreatment steps include: drying the alkali lignin at 100℃~120℃, and then grinding and sieving it to reduce its moisture content to about 15%~20wt% and its particle size to 90~150 mesh.

[0037] The present invention does not limit the specific parameters of the coal coke powder. In the preferred embodiment, in step (1), the water content of the coal coke powder is 15-20 wt%, and the particle size is 90-150 mesh. Its principle and preparation method are similar to those of the alkali lignin mentioned above, and will not be repeated here.

[0038] The present invention does not limit the specific type of oxygen carrier in step (1). Specifically, it can be one or more of Fe-based, Ni-based, Cu-based, and Mn-based.

[0039] The present invention does not limit the specific structure of the oxygen carrier. Specifically, it may include one or more of the following: spinel structure, core-shell structure, and helical structure.

[0040] In a preferred embodiment, the particle size of the oxygen carrier is 0.15–0.4 mm.

[0041] In a preferred embodiment, the oxygen carrier is Fe2O3@Sr3Fe2O 7-x -Ca 0.5 Mn 0.5O composite oxygen carrier and / or CuO@Sr3Fe2O 7-x -Ca 0.5 Mn 0.5 O-complex oxygen carrier, which has a core-shell structure.

[0042] This invention does not limit the specific preparation method of the core-shell composite oxygen carrier; any conventional preparation method in the art can be used. In a specific embodiment, the composite oxygen carrier is prepared using the sol-gel method. More specifically, it is prepared using Fe2O3@Sr3Fe2O3. 7-x -Ca 0.5 Mn 0.5 Taking O-composite oxygen carrier as an example, it is prepared according to the following steps:

[0043] Step A1: Mix strontium nitrate, calcium nitrate, manganese nitrate, ferric nitrate, and water to obtain an aqueous solution;

[0044] Step A2: Mix nano-iron oxide with an aqueous solution of methanol, and then sonicate to obtain a dispersion;

[0045] Step A3: Mix the aqueous solution, the dispersion, citric acid and ethylene glycol, and then dry them at 60-80°C until a sol-like precursor is obtained;

[0046] Step A4: Calcine the precursor to obtain an oxygen carrier.

[0047] The aqueous solution obtained in step A1 is used to prepare the shell structure of the oxygen carrier.

[0048] In a preferred embodiment, in step A4, the calcination temperature is 850–950°C and the calcination time is 5–7 hours.

[0049] In the method described in this invention, CuO@Sr3Fe2O is prepared. 7-x -Ca 0.5 Mn 0.5 The principle of O and Fe2O3@Sr3Fe2O 7-x -Ca 0.5 Mn 0.5 Similar to O, except that in step A2, nano-iron oxide is replaced with nano-copper oxide.

[0050] In a preferred embodiment, in step (1), the weight ratio of the amount of coal coke powder, disposable catalyst and oxygen carrier is 0.5-1.5:1:0.5-1.5.

[0051] In a preferred embodiment, the conditions for the chemical chain gasification reaction in step (1) include: a temperature of 700–1000°C and a time of 30–60 min.

[0052] In the method described in this invention, in step (1), the molar ratio of H2 to CO in the synthesis gas is 1.5 to 2.0.

[0053] In a preferred embodiment, the reaction time in step (2) is 30 to 60 minutes.

[0054] In order to achieve the recycling of oxygen carrier and thus save costs, in a preferred embodiment, the method further includes: calcining the second solid product containing reduced oxygen carrier a obtained in step (2) at 700-1000°C. During the calcination process, the reduced oxygen carrier a recovers lattice oxygen and is then returned to step (1) for reuse as an oxygen carrier.

[0055] More preferably, the calcination time is 60–120 min.

[0056] In the method described in this invention, the chemical looping gasification, chemical looping co-production of CO, and calcination steps are all carried out in a fluidized bed reactor. Thus, the oxygen carrier described in this invention not only provides catalytic oxidation but also acts as a heat carrier, carrying the heat released by the reduced oxygen carrier a during air calcination to the fluidized bed reactor. This allows the CO2 cracking stage for producing high-concentration CO to proceed without external heating, improving energy utilization and further saving costs.

[0057] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0058] In the following examples and comparative examples, the composition and content of the gaseous products obtained in the chemical looping gasification stage and the CO2 cracking stage were measured using a GC9790Plus power analyzer.

[0059] Example 1

[0060] (1) Drying pretreatment: Coal coke powder and disposable catalyst (alkali lignin) are dried at 105℃. After grinding and sieving, their moisture content is reduced to 15wt% and the particle size is 90-150 mesh.

[0061] (2) Preparation of oxygen carrier: Fe2O3@Sr3Fe2O3 was prepared by sol-gel method. 7-x -Ca 0.5 Mn 0.5The O-composite oxygen carrier is prepared by dissolving strontium nitrate, calcium nitrate, manganese nitrate, and ferric nitrate in deionized water to obtain an aqueous solution; ultrasonically treating nano-iron oxide particles in an aqueous methanol solution to obtain an iron oxide dispersion; thoroughly mixing the aqueous solution and the dispersion, and adding citric acid and ethylene glycol while continuously stirring in a constant temperature water bath (80°C) to evaporate the water; transferring the concentrated solution to a desiccator and placing it in a drying oven to dry at 80°C until a sol-like precursor is formed; calcining the precursor in a muffle furnace at 900°C for 6 hours, followed by pulverization and sieving to obtain Fe2O3@Sr3Fe2O3 particles with a particle size of 0.15 mm to 0.40 mm. 7-x -Ca 0.5 Mn 0.5 O-series composite oxygen carriers;

[0062] (3) Chemical chain gasification: The pretreated coal coke powder and alkali lignin in step (1) are chemically chained with the oxygen carrier prepared in step (2) at a ratio of 0.5:1:1.5 to obtain the reaction product. The gasification temperature is 850℃ and the gasification time is 45min. The product obtained from the chemical chain gasification reaction is subjected to gas-solid separation to obtain syngas and a first solid product. The first solid product contains a reducing oxygen carrier and semi-coke.

[0063] (4) CO2 cracking: The first solid product from step (3) is placed in a CO2 atmosphere for high-temperature reaction (temperature set to 800℃, reaction time controlled at 30min). Through further oxidation reaction of CO2 with reducing oxygen carrier and cracking reaction of CO2 with semi-coke, reaction products are obtained. Then, the reaction products are separated into gas and solid to obtain high-concentration CO and a second solid product, wherein the second solid product contains reduced oxygen carrier a.

[0064] (5) Air calcination: The second solid product containing reduced oxygen carrier a in step (4) is placed in an air atmosphere and calcined at high temperature (the temperature is set to 900℃ and the reaction time is controlled at 90min). The reduced oxygen carrier a completely recovers lattice oxygen during the calcination process and is returned to step (3) for recycling reaction to prepare syngas.

[0065] Experimental results: The syngas (i.e., gaseous products) obtained from gas-solid separation during the chemical looping gasification stage contained the following components: H2 24.56%, CO2 14.62%, CO 10.45%, CH4 3.25%, H2 / CO molar ratio 1.84, and syngas yield 1.52m³. 3 / kg, the CO component accounts for 82.1% of the gaseous products obtained in the CO2 cracking stage.

[0066] Examples 2-5

[0067] The method described in Example 1 was implemented, except that the experimental conditions for Examples 2-5 are shown in Table 1 below.

[0068] Table 1

[0069]

[0070]

[0071] Comparative Example 1

[0072] The method described in Example 1 was implemented, except that the discardable catalyst alkali lignin was not added in step (3).

[0073] Specifically, alkali lignin is replaced with an equal amount of coal coke powder, that is, the ratio of coal coke powder to oxygen carrier is 1.5:1.5.

[0074] The experimental results of Examples 1-5 and Comparative Example 1 are shown in Table 2 below. In Table 2, "%" refers to "volume %".

[0075] Table 2

[0076]

[0077] As can be seen from Table 2, the improved method of this invention realizes the chemical chain gasification of coal coke powder and alkali lignin, a byproduct of the papermaking industry, to produce syngas and co-produce high-concentration CO.

[0078] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing syngas and high-concentration CO by chemical looping gasification of coal coke powder, characterized in that, The method includes the following steps: (1) Coal coke powder, disposable catalyst and oxygen carrier are subjected to chemical looping gasification reaction, and the product of the chemical looping gasification is subjected to gas-solid separation to obtain syngas and a first solid product. The syngas contains H2 and CO, and the molar ratio of H2 to CO is 1.5~2.

0. (2) The first solid product is reacted in a CO2 atmosphere at 700~1000℃, and the resulting reaction product is subjected to gas-solid separation to obtain a second solid product and a gaseous product with a CO concentration ≥80% by volume. The disposable catalyst is alkali lignin, and the oxygen carrier is Fe2O3@Sr3Fe2O 7-x -Ca 0.5 Mn 0.5 O composite oxygen carrier and / or CuO@Sr3Fe2O 7-x -Ca 0.5 Mn 0.5 O-composite oxygen carrier, wherein the oxygen carrier has a core-shell structure.

2. The method according to claim 1, characterized in that, In step (1), the alkali lignin has a water content of 15-20 wt% and a particle size of 90-150 mesh; and / or, In step (1), the water content of the coal coke powder is 15~20wt%, and the particle size is 90~150 mesh.

3. The method according to claim 1, characterized in that, In step (1), the particle size of the oxygen carrier is 0.15~0.4mm.

4. The method according to claim 1 or 3, characterized in that, The composite oxygen carrier is prepared according to the following steps: Step A1: Mix strontium nitrate, calcium nitrate, manganese nitrate, ferric nitrate, and water to obtain an aqueous solution; Step A2: Mix nano-iron oxide or nano-copper oxide with an aqueous solution of methanol, and then sonicate to obtain a dispersion; Step A3: Mix the aqueous solution, the dispersion, citric acid and ethylene glycol, and then dry them at 60-80°C until a sol-like precursor is obtained; Step A4: Calcine the precursor to obtain an oxygen carrier.

5. The method according to claim 4, characterized in that, In step A4, the calcination conditions include: a calcination temperature of 850~950℃ and a calcination time of 5~7h.

6. The method according to claim 1, characterized in that, In step (1), the weight ratio of the amount of coal coke powder, disposable catalyst and oxygen carrier is 0.5~1.5:1:0.5~1.

5.

7. The method according to claim 1, characterized in that, In step (1), the conditions for the chemical chain gasification reaction include: a temperature of 700~1000℃ and a time of 30~60min.

8. The method according to claim 1, characterized in that, In step (2), the reaction time is 30~60 min.

9. The method according to claim 1, characterized in that, The method further includes: calcining the second solid product obtained in step (2) at 700~1000℃ and then returning it to step (1) as an oxygen carrier for reuse.

10. The method according to claim 9, characterized in that, The calcination time is 60-120 minutes.

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