A method for improving the production of high-value chemicals from lignite thermal conversion

Abstract

The present application belongs to the technical field of lignite treatment, and particularly relates to a method for improving lignite thermal conversion to produce high-value chemicals. In the present application, in the process of gasification, the catalytic active components in the carbide slag can have synergistic and catalytic effects with the minerals in the lignite. The treatment method provided by the present application can overcome the problems of low energy density, poor gasification efficiency, high tar yield and the like existing in the lignite gasification alone, effectively improves the carbon conversion rate per unit of coal, and greatly advances the reaction temperature zone. In the aspect of coal pyrolysis, the carbide slag can intervene in the pyrolysis reaction path, promote the cracking and conversion of macromolecular organic matter, and be helpful to the production of high-quality tar. The present application fully utilizes the catalysis of the carbide slag on the lignite for gasification or pyrolysis, effectively improves the carbon conversion rate per unit of coal, greatly advances the reaction temperature zone, and simultaneously can directionally regulate and control the production of high-value chemicals in the pyrolysis process, and produce high-quality tar.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lignite treatment, and particularly relates to a method for improving lignite thermal conversion to produce high-value chemicals. BACKGROUND

[0002] Based on the basic characteristics of the resource situation in China (rich in coal, poor in oil, and little gas) and the proportion of lignite in the energy production and consumption structure, the energy structure dominated by lignite will not change for a long time. China is striving to achieve a low-carbon economy and actively participating in global climate and environmental governance. Among them, promoting the efficient use and clean conversion of lignite is one of the important ways to solve the current contradictions.

[0003] In industrial production, various types of waste slag, waste ore, waste metal and the like are continuously accumulated. If the solid waste cannot be properly treated, it will cause serious harm to the environment in many aspects. A large amount of calcium carbide slag will be discharged in the process of producing acetylene, polyvinyl chloride, acetone and other chemical products. The conventional utilization approach only solves the problem of discharging a small amount of calcium carbide slag, and the subsequent treatment of most of the calcium carbide slag has not been solved. Therefore, it is necessary to realize the resource utilization of calcium carbide slag and the like.

[0004] Lignite gasification and pyrolysis technology is one of the ways to effectively utilize lignite. However, the existing lignite gasification technology has the defects of low conversion efficiency and high conversion temperature; at the same time, the existing pyrolysis technology cannot directionally regulate the target product, and the obtained tar has the problems of low hydrocarbon content and high heavy tar component content. SUMMARY

[0005] The purpose of the present application is to provide a method for improving lignite thermal conversion to produce high-value chemicals. The treatment reaction provided by the present application can further improve the gasification conversion effect of lignite and advance the reaction temperature zone; at the same time, it can improve the hydrocarbon content in the tar obtained by pyrolysis, and realize effective regulation of product distribution.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] The present application provides a method for improving lignite thermal conversion to produce high-value chemicals, comprising the following steps:

[0008] Mixing lignite and calcium carbide slag to obtain a mixture;

[0009] Gasifying or pyrolyzing the mixture;

[0010] The mixing method includes mixing method one or mixing method two;

[0011] The mixing method one includes: stirring and mixing lignite, calcium carbide slag and water, and drying to obtain the mixture;

[0012] The mixing method two comprises: mixing the lignite, the carbide slag and water, then performing a hydrothermal reaction, and obtaining the mixture after drying.

[0013] Preferably, the mass ratio of the carbide slag to the lignite is 1:8.5-9.5.

[0014] Preferably, the particle size of the lignite is 200-400 mesh.

[0015] Preferably, the particle size of the carbide slag is 200-400 mesh.

[0016] Preferably, in the mixing method one, the total mass of the lignite and the carbide slag and the amount of water are in a ratio of 1g:8-12 mL, the stirring speed is 380-420 rpm, and the stirring time is 3.5-4.5 h.

[0017] Preferably, in the mixing method two, the total mass of the lignite and the carbide slag and the amount of water are in a ratio of 1g:8-12 mL, the temperature of the hydrothermal reaction is 140-160 ℃, and the time of the hydrothermal reaction is 3.5-4.5 h.

[0018] Preferably, the hydrothermal reaction is performed under stirring, and the stirring speed is 380-420 rpm.

[0019] The hydrothermal reaction is performed in a protective atmosphere.

[0020] Preferably, the gasification conditions comprise: increasing the temperature to a first gasification temperature at a temperature increasing rate of 10 ℃ / min, then increasing the temperature to a second gasification temperature at a temperature increasing rate of 2 ℃ / min, and keeping the temperature at the second gasification temperature.

[0021] The first gasification temperature is 580-620 ℃, and the second gasification temperature is 880-920 ℃.

[0022] The keeping time is 280-320 min.

[0023] During the temperature increasing process, when the temperature is increased to 200 ℃, water is introduced into the reaction system, and the amount of the introduced water is 0.11-0.15 mL / min.

[0024] Preferably, the pyrolysis conditions comprise: a pyrolysis temperature of 580-620 ℃, a temperature increasing rate of 10 ℃ / min for increasing the temperature to the pyrolysis temperature, and a keeping time of 10-15 min.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] In the present application, because the carbide slag contains catalytically active components, in the process of gasification or pyrolysis, the catalytically active components in it can have synergistic and catalytic effects with the minerals in lignite. After mixing the carbide slag and lignite in different ways, the present application can overcome the problems of low energy density, poor gasification efficiency, high tar yield and other problems existing in the gasification of lignite alone, effectively improve the carbon conversion rate per unit of coal, and greatly advance the reaction temperature zone. In terms of coal pyrolysis, carbide slag can intervene in the pyrolysis reaction path, promote the cracking and conversion of macromolecular organic matter, and help produce high-quality tar. At the same time, the product semicoke can be used as a gasification raw material for high-hydrogen synthesis gas production. Therefore, the present application fully utilizes the catalytic effect of carbide slag on lignite for gasification or pyrolysis, effectively improves the carbon conversion rate per unit of coal, greatly advances the reaction temperature zone, and can directionally regulate the production of high-value chemicals and high-quality tar during the pyrolysis process. Moreover, solid waste is low in price and does not need to be considered for recycling, further realizing the resource utilization of solid waste materials.

[0027] Compared with the simple mixing of lignite and carbide slag, the present application uses two methods, impregnation (mixing method one) and hydrothermal (mixing method two), to mix carbide slag and lignite before gasification or pyrolysis. These two mixing methods can greatly advance the reaction temperature zone, significantly improve the carbon conversion rate, precisely regulate the distribution of pyrolysis products, produce high-quality tar, and greatly improve the thermal reaction performance of lignite. Most importantly, it realizes the efficient utilization of waste solid waste, which has important significance for resource utilization, energy saving and emission reduction. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 For sample ML + -CS-NTP gasification reaction gas generation rate graph;

[0029] Figure 2 For sample ML + -CS-150℃ gasification reaction gas generation rate graph;

[0030] Figure 3 For sample ML + gasification reaction gas generation rate graph;

[0031] Figure 4 For sample ML + -CS gasification reaction gas generation rate graph;

[0032] Figure 5 For ML + , ML + -CS, ML + -CS-NTP, ML + -CS-150℃ carbon conversion rate generation graph;

[0033] Figure 6 For ML+ ML + -CS, ML + -CS-NTP, ML + - CS-150℃ thermogravimetric diagram;

[0034] Figure 7 For ML + ML + -CS, ML + -CS-NTP, ML + -Distribution diagram of three products of pyrolysis of CS-150℃;

[0035] Figure 8 For ML + ML + -CS, ML + -CS-NTP, ML + -CS-150℃ pyrolysis tar different types of proportions. DETAILED DESCRIPTION

[0036] The present invention provides a method for improving the thermal conversion of lignite to produce high-value chemicals, comprising the following steps:

[0037] mixing lignite and carbide slag to obtain a mixture;

[0038] gasifying or pyrolyzing the mixed material;

[0039] The mixing method includes mixing method 1 or mixing method 2;

[0040] The first mixing method comprises: stirring and mixing lignite, carbide slag and water, and drying to obtain the mixture;

[0041] The second mixing method comprises: mixing lignite, carbide slag and water, performing a hydrothermal reaction, and obtaining the mixture after drying.

[0042] The invention mixes lignite and carbide slag to obtain a mixture.

[0043] In the present application, before the mixing, the lignite and the carbide slag are preferably subjected to pretreatment respectively. In the present application, the pretreatment of the lignite preferably comprises: sequentially subjecting the lignite to crushing, first drying, ball milling, screening, second drying, acid washing, water washing and third drying. In the present application, the crushing is preferably performed in a jaw crusher; the temperature of the first drying is preferably 105 ℃; the temperature of the second drying is preferably 105 ℃, and the time is preferably 5 h. In the present application, the acid washing preferably employs hydrochloric acid solution; the mass concentration of the hydrochloric acid solution is preferably 18%; the usage ratio of the lignite powder to the acid solution is preferably 1 g:10 mL; the acid washing is preferably performed under stirring, the stirring speed is preferably 400 rpm, and the time is preferably 12 h; the water washing is preferably performed using deionized water; the present application does not have special limitation on the number of the water washing, until there is no Cl - in the washing liquid, and the third drying temperature is preferably 105 ℃, and the time is preferably 24 h. In the present application, the particle size of the lignite is preferably 200-400 mesh.

[0044] In the present application, the pretreatment of the carbide slag preferably comprises: sequentially subjecting the carbide slag to crushing, pre-drying, ball milling, screening and drying. In the present application, the crushing is preferably performed in a jaw crusher; the temperature of the pre-drying is preferably 105 ℃; the temperature of the drying is preferably 105 ℃, and the time is preferably 5 h. In the present application, the particle size of the carbide slag is preferably 200-400 mesh.

[0045] In the present application, the mass ratio of the carbide slag to the lignite is preferably 1:8.5-9.5, and is further preferably 1:9.

[0046] In the present application, the mixing mode comprises mixing method one or mixing method two.

[0047] In the present application, the mixing method one comprises: stirring and mixing the lignite, the carbide slag and water, and obtaining the mixture after drying. In the present application, the usage ratio of the total mass of the lignite and the carbide slag to water is preferably 1 g:8-12 mL, the stirring and mixing speed is preferably 380-420 rpm, and the time is preferably 3.5-4.5 h.

[0048] In the present application, the mixing method two comprises: mixing lignite, carbide slag and water, then carrying out hydrothermal reaction, and obtaining the mixture after drying. In the present application, the total mass of the lignite and the carbide slag and the amount of the water are preferably 1 g: 8-12 mL, the temperature of the hydrothermal reaction is preferably 140-160 ℃, and the time is preferably 3.5-4.5 h. In the present application, the hydrothermal reaction is preferably carried out under stirring, and the stirring speed is preferably 380-420 rpm; the hydrothermal reaction is preferably carried out under a protective atmosphere, and the protective atmosphere is preferably argon.

[0049] In the present application, the conditions of the gasification preferably comprise: heating to a first gasification temperature at a heating rate of 10 ℃ / min, then heating to a second gasification temperature at a heating rate of 2 ℃ / min, and keeping the temperature at the second gasification temperature; the first gasification temperature is preferably 580-620 ℃, and further preferably 600 ℃; the second gasification temperature is preferably 880-920 ℃, and further preferably 900 ℃; the keeping time is preferably 280-320 min, and further preferably 300 min; in the process of heating, when the temperature is heated to 200 ℃, water is introduced into the reaction system, and the amount of the water introduced is 0.11-0.15 mL / min, and further preferably 0.13 mL / min. In the present application, argon is preferably used as the carrier gas in the process of the gasification, and the flow rate of the carrier gas is preferably 200 mL / min.

[0050] In the present application, the conditions of the pyrolysis preferably comprise: a pyrolysis temperature of 580-620 ℃, and further preferably 600 ℃, a heating rate of 10 ℃ / min for heating to the pyrolysis temperature, and a keeping time of 13-17 min, and further preferably 15 min. In the present application, argon is preferably used as the carrier gas in the process of the pyrolysis, and the flow rate of the carrier gas is preferably 100 mL / min.

[0051] Unless otherwise specified, the materials and equipment used in the present application are commercially available in the art.

[0052] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0053] In the following examples and comparative examples, the lignite is Manglai lignite from Xilingol, and the carbide slag is from Inner Mongolia.

[0054] In the present application, the composition of the carbide slag is shown in Table 1.

[0055] Table 1 Composition of carbide slag (CS) wt.

[0056]

[0057] Example 1

[0058] Firstly, the Mongolian lignite was crushed by a jaw crusher, then pre-dried at 105 ℃ in a blast drying oven, and then made into powder by a ball mill, and finally sieved to 200-400 mesh by a sifter. The sieved lignite was dried at 105 ℃ for 5 h to obtain a coal sample, denoted as (ML);

[0059] The above treated ML was mixed with 18wt% HCl at a ratio of 1 g: 10 mL, and stirred at a speed of 400 rpm for 12 h, and then repeatedly washed with deionized water, and the coal cake was suction filtered until there was no Cl - (AgNO3 detection) in the washing liquid. The filter cake was dried at 105 ℃ for 24 h to obtain an acid-washed coal sample, denoted as (ML + );

[0060] The composition of the acid-washed coal sample is shown in Table 2.

[0061] Table 2 Composition of acid-washed coal sample

[0062]

[0063] Wherein, ad-air dried basis; M-moisture; A-ash; V-volatile matter; FC-fixed carbon.

[0064] The carbide slag was crushed by a jaw crusher, then pre-dried at 105 ℃ in a blast drying oven, and then made into powder by a ball mill, and finally sieved to 200-400 mesh by a sifter. The sieved carbide slag powder was dried at 105 ℃ for 12 h to obtain a carbide slag sample, denoted as (CS);

[0065] The above obtained ML + was mixed with CS at a mass ratio of 9:1, and the mixed sample was mixed with deionized water at a volume ratio of 1 g: 10 mL, and stirred at a speed of 400 rpm for 4 h, and then the mixed liquid was placed in a blast drying oven at 105 ℃ for drying to obtain a gasification material sample, denoted as: ML + -CS-NTP;

[0066] 0.5 g of sample ML + ​-CS-NTP was put into the reactor, Ar was used as the carrier gas, the gas velocity was 200 mL / min; the reactor was heated from room temperature to 200 ℃ (heating rate: 10 ℃ / min, heating time: 20 min), deionized water was introduced at a rate of 0.013 mL / min, and the temperature was continued to rise to 600 ℃ (heating rate: 10 ℃ / min, heating time: 40 min), and then the temperature was raised to 900 ℃ (heating rate: 2 ℃ / min, heating time: 150 min) and kept constant until the reaction was completed; the generated gas was analyzed by a gas chromatograph;

[0067] Sample ML + The gas generation rate diagram of the gasification reaction of CS-NTP is shown in Figure 1 From Figure 1 It can be seen that in the water vapor gasification reaction, the main generated gas is CO2 and H2, and the generation rate of H2 is the highest, and ML + The gas generation rate of CS-NTP reaches the maximum at 680 ℃, indicating that the gasification reaction rate of the sample reaches at 680 ℃;

[0068] 3 g of sample ML + -CS-NTP was put into the pyrolysis furnace, Ar was used as the carrier gas, and the gas velocity was 100 mL / min. The pyrolysis furnace was heated from room temperature to 600 ℃ (heating rate: 10 ℃ / min, heating time: 60 min), and kept constant for 15 min. The volatile matter was condensed and collected by a cold trap, and the tar component was dissolved in CH2Cl2 and identified by Agilent Technologies 7890B-5977 GC-MS instrument.

[0069] Example 2

[0070] The coal bottom sample (ML), the acid-washed coal bottom sample (ML + ) and the carbide slag bottom sample (CS) were obtained in the manner of Example 1, respectively;

[0071] The ML + and CS obtained above were mixed in a mass ratio of 9:1, and the mixed sample was mixed with deionized water in a volume ratio of 1 g:10 mL and put into a reaction kettle, nitrogen was introduced into the reaction kettle to exclude air in the reaction kettle (three times), then the reaction kettle was heated to 150 ℃ at a heating rate of 10 ℃ / min, and kept constant for 4 h, the stirring was started at the beginning of the reaction, and the rotation speed was 400 rpm until the end of the reaction, finally the reaction liquid was dried in a forced air drying oven at 105 ℃, and a gasification sample was obtained, which was recorded as: ML + -CS-150 ℃;

[0072] Take 0.5 g of sample ML + -CS-150℃ into the reactor, with Ar as the carrier gas, gas velocity is 200 mL / min; the reactor from room temperature to 200 ℃ (heating rate: 10 ℃ / min, heating time: 20 min), with 0.013 mL / min of deionized water, continue to heat to 600 ℃ (heating rate: 10 ℃ / min, heating time: 40 min), then heat to 900 ℃ (heating rate: 2 ℃ / min, heating time: 150 min) until the reaction is completed; the generated gas is analyzed by gas chromatograph;

[0073] Sample ML + -CS-150℃ gasification reaction of the gas production rate chart as shown in Figure 2 Figure 2 It can be seen that: in the water vapor gasification reaction, the main gas generated is CO2 and H2, the generation rate of H2 is the highest, and ML + -CS-150℃ gas generation rate reaches the maximum at 680 ℃, indicating that the sample gasification reaction rate reaches the highest at 680 ℃;

[0074] Take 3 g of sample ML + -CS-150℃ into the pyrolysis furnace, with Ar as the carrier gas, gas velocity is 100 mL / min. The pyrolysis furnace from room temperature to 600 ℃ (heating rate: 10 ℃ / min, heating time: 60 min), constant temperature for 15 min. The volatile matter is condensed and collected by a cold trap, and the tar components are dissolved in CH2Cl2 and identified by Agilent Technologies 7890B-5977 GC-MS instrument.

[0075] Comparative Example 1

[0076] The coal bottom sample (ML) and the acid-washed coal bottom sample (ML + ) are obtained in the manner of Example 1, respectively;

[0077] Take 0.5 g of sample ML + into the reactor, with Ar as the carrier gas, gas velocity is 200 mL / min. The reactor from room temperature to 200 ℃ (heating rate: 10 ℃ / min, heating time: 20 min), with 0.013 mL / min of deionized water, continue to heat to 600 ℃ (heating rate: 10 ℃ / min, heating time: 40 min), then heat to 900 ℃ (heating rate: 2 ℃ / min, heating time: 150 min) until the reaction is completed; the generated gas is analyzed by gas chromatograph; ​

[0078] Sample ML + The generation rate of the gas generated by the gasification reaction is shown in the figure Figure 3 As shown, from Figure 3 It can be seen that in the steam gasification reaction, the main generated gases are CO2 and H2, and the generation rate of H2 is the highest. + The gas generation rate reaches the maximum at 860 ℃, indicating that the gasification reaction rate of the sample reaches the highest at 860 ℃;

[0079] Weigh 3g sample ML + The sample was placed in a pyrolysis furnace with Ar as the carrier gas at a rate of 100 mL / min. The temperature was raised from room temperature to 600°C (at a heating rate of 10°C / min for 60 min) and held at that temperature for 15 min. The volatiles were condensed in a cold trap to collect the tar. The tar components were dissolved in CH2Cl2 and identified using an Agilent Technologies 7890B-5977 GC-MS instrument.

[0080] Comparative Example 2

[0081] According to the method of Example 1, the coal bottom sample (ML), the acid-washed coal bottom sample (ML + ) and carbide slag bottom sample (CS);

[0082] Take the ML obtained above + Mixed with CS in a mass ratio of 9:1 to obtain a gasified material sample, denoted as: ML + -CS;

[0083] Weigh 0.5 g of sample ML + -CS was placed in a reactor, and Ar was used as a carrier gas at a gas rate of 200 mL / min. The reactor was heated from room temperature to 200 °C (heating rate: 10 °C / min, heating time: 20 min), and deionized water was introduced at a rate of 0.013 mL / min. The temperature was further increased to 600 °C (heating rate: 10 °C / min, heating time: 40 min), and then to 900 °C (heating rate: 2 °C / min, heating time: 150 min) and maintained at this temperature until the reaction was completed. The generated gas was analyzed by gas chromatography.

[0084] Sample ML + The generation rate of the gas generated by the gasification reaction of -CS is shown in the figure Figure 4 As shown, from Figure 4 It can be seen that in the steam gasification reaction, the main generated gases are CO2 and H2, and the generation rate of H2 is the highest. +The gas generation rate of -CS reached the maximum at 790°C, indicating that the gasification reaction rate of the sample reached the highest at 790°C.

[0085] 3g sample ML was weighed + -CS was placed in a pyrolysis furnace, with Ar as the carrier gas at a gas velocity of 100 mL / min. The pyrolysis furnace was heated from room temperature to 600°C (heating rate: 10°C / min, heating time: 60 min), and kept at 600°C for 15 min. The volatile matter was condensed and collected by a cold trap, and the tar components were dissolved in CH2Cl2, and then identified by Agilent Technologies 7890B-5977 GC-MS instrument.

[0086] Results analysis:

[0087] (1) Figure 5 ML + (Comparative Example 1), ML + -CS (Comparative Example 2), ML + -CS-NTP (Example 1), ML + -CS-150°C (Example 2) carbon conversion rate generation graph;

[0088] Figure 5 The carbon conversion rate generation of ML + , ML + -CS, ML + -CS-NTP, ML + -CS-150°C was detailed. Specifically, under the reaction condition of 900°C, the ML + sample without adding carbide slag had a carbon conversion rate of only 56.8%, while after introducing and mixing with carbide slag, the carbon conversion rate at this temperature was significantly improved to 84.6%, with an increase of 27.8%. Further, after the impregnation (Example 1) and hydrothermal (Example 2) treatment methods, the sample could basically complete the reaction process at 800°C, with a carbon conversion rate exceeding 95%, showing high-efficiency gasification reaction characteristics.

[0089] (2) Figure 6 ML + (Comparative Example 1), ML + -CS (Comparative Example 2), ML + -CS-NTP (Example 1), ML + -CS-150°C (Example 2) thermogravimetric graph;

[0090] It can be seen from Figure 6 that the ML +The weight loss rate of the sample reaches its peak at 910 ℃, and after mixing with carbide slag, the reaction temperature zone shifts significantly forward to 820 ℃, which is much higher than that of ML. + In the case of gasification alone, the temperature shifted forward by 90 °C. On this basis, after impregnation and hydrothermal treatment, the reaction temperature was further advanced to 680 °C and 680 °C respectively, which is significantly higher than that of ML. + The individual gasification reaction temperature zones advanced by 210°C and 210°C, respectively, demonstrating the significant optimization effect of the aforementioned treatment on the reaction temperature zone, greatly promoting the gasification reaction to proceed at a lower temperature range. This highlights the effective regulation of the gasification reaction temperature zone by the treatment method.

[0091] (3) Figure 7 For ML + (Comparative Example 1), ML + -CS (Comparative Example 2), ML + -CS-NTP (Example 1), ML + - Distribution diagram of three products of pyrolysis of CS-150℃ (Example 2);

[0092] Depend on Figure 7 It can be seen that ML + The yields of solid, liquid and gas products were 62.7%, 17.3% and 20.0% respectively. After adding carbide slag, the product distribution of samples treated by different methods changed significantly. + The solid and liquid yields of -CS increased to 64.5% and 20.9% respectively, while the gas yield decreased significantly to 14.6%. This may be because the introduction of carbide slag hinders the rapid escape of volatile matter in lignite through physical adsorption or surface coating. At the same time, the calcium-based additives (such as CaO) generated by carbide slag during the heating process can preferentially adsorb acidic gases (such as CO2) generated by pyrolysis, inhibiting the secondary cracking reaction, thereby retaining more liquid tar. In contrast, ML + -CS-NTP and ML + The solid yield and gas yield of the two samples of -CS-150℃ increased to 67.8%, 67.1% and 22.9%, 20.5%, respectively, while the liquid yield decreased significantly to 11.3% and 12.4%. It may be that these two treatments caused the Ca in CS to 2+ Ion exchange or complexation with the oxygen-containing functional groups (-COOH, -OH) in lignite forms a cross-linked structure with increased thermal stability, inhibiting liquid condensation and promoting gas generation. Overall, the different treatment methods significantly altered the distribution of the gas-liquid-solid three-phase products during the pyrolysis of Manglai lignite.

[0093] (4) Figure 8 For ML + (Comparative Example 1), ML+ -CS (Comparative Example 2), ML + -CS-NTP (Example 1), ML + - CS-150℃ (Example 2) pyrolysis tar of different types;

[0094] Depend on Figure 8 It can be seen that different treatment methods have a significant effect on the relative content of various compounds in tar. First, most of the substances in pyrolysis coal tar belong to alcohols / phenols / ethers and hydrocarbons. + The proportion of alcohols / phenols / ethers in the sample was 75.99%, which was reduced to 72.99% after adding carbide slag for simple mixing. + -CS-NTP, ML + -CS-150℃, the proportion of alcohols / phenols / ethers decreased significantly to 61.37% and 62.85% respectively. + -CS-NTP, ML + -CS-150℃, the proportion of hydrocarbons increased from 13.47% in ML+ to 25.75 and 22.09% in ML+, respectively. + -Hydrocarbon content of CS and ML + There is no significant difference in the content of aldehydes / ketones, carboxylic acids / esters and other types in the overall coal pyrolysis tar. The two treatment methods of impregnation and hydrothermal treatment change the chemical environment and pyrolysis conditions of the coal to reduce the content of Ca in the carbide slag. 2+ The ion exchange behavior with coal significantly affects the pyrolysis process of coal. 2+ It can bind to oxygen atoms in coal to form stable complexes, thereby altering the coal's chemical reaction pathways, promoting the formation of aromatic compounds while inhibiting the formation of oxygen-containing compounds (such as alcohols, phenols, and ethers), thereby promoting their conversion to hydrocarbons. Simple mixing, on the other hand, has little effect on the coal structure, only slightly altering the composition through physical adsorption, resulting in a pyrolysis product composition similar to that of untreated coal. This suggests that the addition of carbide slag and different treatment methods can significantly influence the formation pathways of alcohols, phenols, ethers, and hydrocarbons during coal pyrolysis.

[0095] Based on the above experimental results, the following conclusions can be drawn: carbide slag has significant catalytic effect on lignite gasification process. However, the catalytic effect achieved by different addition methods is significantly different. Among them, the catalytic promotion effect is the weakest when added by simple mixing method, and in some cases it is difficult to effectively promote the gasification reaction process. In comparison, impregnation and hydrothermal treatment show the most excellent catalytic effect, which can make the gasification reaction efficiently carried out at a lower temperature range, achieve higher carbon conversion rate, and the optimization effect on lignite steam gasification is the most outstanding. At the same time, in the pyrolysis process, different treatment methods can direct the distribution of products, and impregnation and hydrothermal treatment can obtain more solid and gas products. In the composition of tar, impregnation and hydrothermal treatment can produce more light tar, which further produces high-value chemicals, providing an important path for clean utilization of coal.

[0096] Although the above embodiments have made a detailed description of the present application, it is only a part of the embodiments of the present application, not all the embodiments, and other embodiments can be obtained under the premise of not being creative according to the present embodiments, which belong to the protection scope of the present application.

Claims

1. A method for improving the production of high-value chemicals by thermal conversion of lignite, characterized in that: The steps are: mixing lignite and carbide slag to obtain a mixed material; gasifying or pyrolyzing the mixed material; The mixing comprises: mixing lignite, carbide slag and water, performing a hydrothermal reaction, and drying to obtain the mixture; The ratio of the total mass of the lignite and carbide slag to water is 1g:8-12mL, the temperature of the hydrothermal reaction is 140-160°C, and the time is 3.5-4.5h; The hydrothermal reaction is carried out under stirring, and the stirring speed is 380-420 rpm; The hydrothermal reaction is carried out under a protective atmosphere.

2. The method according to claim 1, characterized in that The mass ratio of the carbide slag to the lignite is 1:8.5-9.

5.

3. The method according to claim 1 or 2, characterized in that The particle size of the lignite is 200-400 meshes.

4. The method according to claim 1 or 2, characterized in that The particle size of the carbide slag is 200-400 meshes.

5. The method according to claim 1, wherein The gasification conditions include: heating to a first gasification temperature at a heating rate of 10°C / min, then heating to a second gasification temperature at a heating rate of 2°C / min, and maintaining the temperature at the second gasification temperature; The first gasification temperature is 580-620° C., the second gasification temperature is 880-920° C.; the holding time is 280-320 min; During the heating process, when the temperature reaches 200° C., water is introduced into the reaction system at a rate of 0.11 to 0.15 mL / min.

6. The method according to claim 1, characterized in that The pyrolysis conditions include: a pyrolysis temperature of 580-620° C., a heating rate of 10° C. / min to the pyrolysis temperature, and a holding time of 10-15 min.

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