Novel method for efficiently preparing ethylene glycol by using coal pyrolysis byproducts

Abstract

The invention relates to the technical field of ethylene glycol preparation, and particularly discloses a novel method for efficiently preparing ethylene glycol by using coal pyrolysis byproducts, which comprises the following steps: carrying out temperature programming pyrolysis reaction on coal to obtain tar byproducts rich in light aromatic hydrocarbons; carrying out supercritical fluid extraction separation on the tar byproduct to obtain a high-purity light aromatic hydrocarbon mixture; carrying out directional catalytic oxidation on the aromatic hydrocarbon mixture to obtain an oxalic acid product; carrying out esterification reaction on the oxalic acid product and an alcohol substance in an ultrasonic field to obtain an oxalate product; carrying out catalytic hydrogenation reaction on the oxalate product to obtain a crude ethylene glycol product; and purifying the crude ethylene glycol product to obtain the target product ethylene glycol, in the esterification reaction, the ultrasonic field is utilized to strengthen mass transfer and break through the equilibrium limitation of the traditional esterification reaction, so that molecules in the reaction system are rapidly mixed, the reaction time is shortened, the conversion efficiency is improved, the limitation of molecular diffusion can be effectively overcome, and the reaction rate is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of ethylene glycol preparation, and particularly relates to a new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis. Background Art

[0002] With the adjustment of the energy structure and the increasing demand of the chemical industry for sustainable development, the efficient preparation of high-value-added chemicals by using coal-based resources has become a research hotspot. Ethylene glycol (EG), as an important organic chemical raw material, is widely used in fields such as polyester fiber, antifreeze, and solvents. Traditional ethylene glycol production mainly relies on the petroleum route, which has problems such as dependence on imported raw materials, high process energy consumption, and large carbon emissions. In recent years, the coal-based ethylene glycol preparation technology based on coal pyrolysis has gradually become an important direction to replace the petroleum route due to its advantages such as wide raw material sources, short process flow, and high carbon utilization rate. However, there are still some deficiencies in the existing coal-based ethylene glycol preparation technology:

[0003] The tar by-products generated by coal pyrolysis have complex compositions, containing polycyclic aromatic hydrocarbons, light aromatic hydrocarbons, and heteroatom compounds. Although the traditional organic solvent extraction method can separate some aromatic hydrocarbons, it has problems such as poor selectivity, solvent residue, and high separation cost, resulting in low yield and insufficient purity of light aromatic hydrocarbons, making it difficult to meet the raw material requirements of subsequent catalytic oxidation reactions. The oxidation of aromatic hydrocarbons to prepare oxalic acid is a key step in the coal-based ethylene glycol route, but there is a problem of insufficient control of the oxidation depth in the existing catalytic system. In a conventional fixed-bed reactor, uneven oxygen concentration distribution easily leads to over-oxidation to generate by-products such as CO2, and the active sites of the catalyst are easily deactivated due to carbon deposition or sintering, resulting in an oxalic acid selectivity of less than 70% and limited yield of the target product. In addition, there is a lack of effective energy coupling between unit operations such as coal pyrolysis, oxidation, esterification, and hydrogenation, and the reaction waste heat is not fully utilized, resulting in relatively high overall energy consumption. For example, the esterification reaction requires external heating, and the steam waste heat generated by chemical looping reforming is often directly discharged, causing energy waste.

[0004] In view of this, the inventor proposes a new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis, comprising:

[0008] Performing a programmed temperature pyrolysis reaction on coal to obtain a tar by-product rich in light aromatic hydrocarbons;

[0009] The supercritical fluid extraction and separation is carried out on the tar by-products to obtain a high-purity light aromatic hydrocarbon mixture;

[0010] The aromatic hydrocarbon mixture is subjected to directional catalytic oxidation to obtain an oxalic acid product;

[0011] The oxalic acid product and an alcohol substance are subjected to an esterification reaction in an ultrasonic field by establishing a mass transfer enhancement model for ultrasonic enhanced esterification reaction to obtain an oxalic acid ester product;

[0012] The oxalic acid ester product is subjected to catalytic hydrogenation reaction to obtain a crude ethylene glycol product;

[0013] The crude ethylene glycol product is purified to obtain the target product ethylene glycol.

[0014] Preferably, the supercritical fluid extraction method uses supercritical carbon dioxide as an extractant, and the tar by-products are subjected to gradient separation by adjusting the pressure range to 8 - 30 MPa and the temperature to 40 - 80 °C to obtain a light aromatic hydrocarbon mixture with a yield of not less than 92%.

[0015] Preferably, the supercritical fluid extraction method realizes automatic control by real-time monitoring of pressure, temperature and time and cooperating with online data feedback to ensure accurate cutting of by-product components and support high-selectivity conversion in the subsequent reaction stage. The calculation formula for the extraction efficiency E is:

[0016] E=(1 - e -α(P-Pmin) )·(1 - e -β(T-Tmin) )·(1 - e -γt )

[0017] E: Extraction efficiency, representing the relative yield of selectively extracting light aromatic hydrocarbons from tar by-products (the value range is 0 to 1, and multiplying by 100% is the percentage yield);

[0018] P: Operating pressure during the extraction process, unit: MPa, generally in the range of 8 - 30 MPa in the current process;

[0019] Pmin: The minimum pressure required to achieve preliminary effective extraction;

[0020] T: Extraction temperature, unit: °C, the process temperature range is 40 - 80 °C;

[0021] Tmin: The minimum temperature at which effective dissolution and mass transfer start to be achieved;

[0022] t: Supercritical extraction time (unit: seconds or minutes, selected according to the actual process);

[0023] α, β, γ: Empirical constants, respectively reflecting the sensitivity of pressure, temperature and time to the extraction efficiency, determined by experimental calibration;

[0024] The above formula describes the influence of regulating pressure, temperature, and time on the selective extraction of light aromatics under supercritical CO2 conditions. Each term in the formula adopts an exponential growth model, reflecting the phenomenon that the efficiency gradually tends to saturation after the parameters reach a certain threshold. Using this formula, the following can be achieved:

[0025] Process parameter optimization: After determining α, β, and γ through experiments, the extraction efficiency under different operating conditions can be predicted and regulated, thereby ensuring a high-purity yield of light aromatics (>92%).

[0026] Process control: Monitor pressure, temperature, and time in real-time, and cooperate with online data feedback to achieve automatic regulation, ensuring precise cutting of by-product components and supporting highly selective conversion in the subsequent reaction stage.

[0027] Preferably, the directional catalytic oxidation uses a supported nanocatalyst containing CeO2-MoO3, conducts a gas-solid reaction in a microchannel reactor, and adopts an oxygen concentration gradient catalytic oxidation reaction rate model to control the oxygen supply method with a gradient of oxygen concentration from 15% to 30%, so that the conversion rate of benzene-based aromatics is higher than 85% and the selectivity of oxalic acid is higher than 78%.

[0028] Preferably, the calculation formula of the oxygen concentration gradient catalytic oxidation reaction rate model is:

[0029] X = 1 - e-keffτ

[0030] keff = k0·f(O2) and

[0031] where, X: reaction conversion rate, representing the proportion of light aromatics converted to oxalic acid;

[0032] τ: reaction residence time (unit: seconds or hours);

[0033] k0: basic reaction rate constant, reflecting the reaction rate under standard oxygen concentration conditions;

[0034] O2: oxygen concentration in the reactor (percentage), and this process adopts gradient regulation (gradually increasing from 15% to 30%);

[0035] O2,crit: critical oxygen concentration, when exceeding this value, the reaction is prone to over-oxidation to generate CO2; this parameter is determined according to the characteristics of the catalytic system (for example, 20%);

[0036] δ: slope parameter, used to describe the sensitivity of the influence of oxygen concentration on the reaction rate;

[0037] The model is corrected based on ideal reaction kinetics, with a focus on introducing the oxygen concentration gradient control factor f(O2), which inhibits the reaction rate when the oxygen concentration is too high, thereby preventing over-oxidation. Its significance lies in:

[0038] Precisely control the catalytic reaction: By dynamically regulating the oxygen concentration, the conversion rate of benzene-based aromatics can be achieved > 85% while the oxalic acid selectivity reaches 78%, improving the product selectivity.

[0039] Process safety and stability: Avoid catalyst deactivation or by-product formation under high oxygen concentration conditions, making the overall reaction process smoother and more controllable.

[0040] Process simulation and optimization: By real-time monitoring of the oxygen concentration and reaction time, the oxygen supply strategy can be adjusted according to the model to achieve the best reaction efficiency.

[0041] Preferably, in the esterification reaction, the oxalic acid product and methanol are mixed at a molar ratio of 1:4, an ionic liquid containing a sulfonic acid group is used as the catalyst, and an ultrasonic field with a frequency of 40 kHz is used for reaction intensification, shortening the esterification reaction time to 1.5 hours and increasing the esterification rate to 99.2%.

[0042] Preferably, the formula for the mass transfer enhancement model of the ultrasonic intensification esterification reaction is:

[0043]

[0044] or

[0045] where kL: actual mass transfer coefficient (unit: m / s or cm / s), representing the improvement effect of the ultrasonic field on the mass transfer rate;

[0046] kL0: reference mass transfer coefficient, the mass transfer rate under the condition of no ultrasonic field;

[0047] PUS: ultrasonic power density, unit: W / cm 2 , or the effective power of the ultrasonic field, whose value is related to the output power and frequency of the ultrasonic device (40 kHz in this process);

[0048] ξ, μ: empirical parameters, respectively representing the intensity and response index of the ultrasonic power on mass transfer enhancement, obtained by fitting experimental data;

[0049] η: enhancement factor, reflecting the logarithmic effect of the ultrasonic field on mass transfer enhancement;

[0050] P0: reference power density parameter;

[0051] In the oxalic acid esterification reaction, the purpose of introducing the ultrasonic field is to break the traditional esterification equilibrium, enhance mass transfer, and accelerate the reaction process. Through this model, it can:

[0052] Quantitative evaluation of the ultrasonic effect: Clearly show how the mass transfer coefficient is improved under different ultrasonic power conditions, so that the esterification time is shortened from the traditional 4 hours to 1.5 hours, and the esterification rate is increased to 99.2%.

[0053] Optimization of process parameters: Based on the relationship of the improved mass transfer coefficient, the optimal ultrasonic power density and reactor design parameters can be determined to ensure that the reaction reaches the optimal efficiency under the condition of enhanced mass transfer.

[0054] Reduce energy consumption and the risk of reaction imbalance: Utilize the ultrasonic effect to achieve local efficient mixing and mass transfer, reduce the macroscopic mass transfer resistance and the phenomenon of too high local concentration, ensure the uniform progress of the reaction, and further improve the product yield and purity.

[0055] Preferably, the catalytic hydrogenation reaction uses a Cu / SiO2 - Al2O3 catalyst and is carried out in a multi-stage fixed-bed reactor. The reaction temperature is 200 °C, the pressure is 3.0 MPa, and the liquid hourly space velocity is 0.8 h -1 , and the obtained crude ethylene glycol product reaches a purity of more than 99.9% after subsequent treatment.

[0056] Preferably, the gas produced during the coal pyrolysis process is purified by membrane separation to obtain methane with a purity higher than 95%, which is used for chemical looping reforming reaction to produce hydrogen, and the generated hydrogen is used in the catalytic hydrogenation reaction step. The chemical looping reaction uses Fe2O3 - CeO2 as the oxygen carrier, and the volume fraction ratio of H2 / CO is controlled to be 2:1 by adjusting the reaction conditions.

[0057] Preferably, the steam by-produced in the chemical looping reaction is introduced into the esterification reaction step after heat exchange and reused as a heat source to achieve the recycling of system energy.

[0058] Compared with the prior art, the beneficial effects of the present invention are:

[0059] (1) Through the front-end programmed temperature pyrolysis reaction, under the regulation of the temperature gradient and the assistance of the catalyst, the tar components in the coal pyrolysis products are reasonably distributed and rich in light aromatics. Applying the supercritical CO2 dynamic extraction process, using the gradient regulation of pressure, temperature and time, the precise directional separation of light aromatics in tar is realized. This method has advantages in both chemical phase equilibrium and mass transfer kinetics, can overcome the problems such as poor selectivity and solvent residue in traditional organic solvent extraction, provide high-purity raw materials for downstream reactions, and reduce the interference of by-product impurities.

[0060] (2) The present invention utilizes a microchannel reactor to achieve high surface area gas-solid contact, assisted by nanoscale catalysts and oxygen concentration gradient control strategies, so as to achieve targeted oxidation of aromatic hydrocarbons to generate target oxalic acid, avoid over-oxidation to generate useless by-products, and introduce an oxygen concentration dynamic control model to fundamentally adjust the reaction rate and selectivity, improve conversion efficiency, and ensure the stability of the product molecular structure, which has significant theoretical advantages in oxidation reactions.

[0061] (3) In the esterification reaction, the present invention utilizes the ultrasonic field to enhance mass transfer, breaking the equilibrium limitation of the traditional esterification reaction, allowing the molecules in the reaction system to mix rapidly, thereby shortening the reaction time and improving the conversion efficiency. Ultrasonic waves cause microscale cavitation effects and local high temperature and high pressure phenomena under the action of the physical field, which can effectively overcome the limitation of molecular diffusion and promote the reaction rate, thereby achieving high reaction conversion in a shorter time and reducing the reaction energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 The present invention is a flow chart of a new method for efficiently preparing ethylene glycol using coal pyrolysis byproducts. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] Embodiment 1:

[0065] See also Figure 1 As shown, a new method for efficiently preparing ethylene glycol using coal pyrolysis byproducts comprises:

[0066] 1. Device system:

[0067] Programmed temperature pyrolysis reactor: equipped with a precision temperature control system (error ±2°C) and an online gas analyzer (using a mass spectrometer to monitor the composition of the generated gas in real time).

[0068] Supercritical CO2 extraction device: Use high-pressure reactor (working pressure up to 35MPa), online pressure and temperature sensors, and data acquisition instrument to achieve real-time monitoring.

[0069] Microchannel gas-solid reactor: Built-in oxygen concentration sensor and flow meter can record gas concentration and reaction residence time in real time.

[0070] Ultrasonic enhanced reactor: equipped with a 40kHz ultrasonic module and an online reaction monitoring system, the esterification products are detected by GC-MS and HPLC after sampling.

[0071] Fixed-bed catalytic hydrogenation unit: The temperature, pressure, and liquid hourly space velocity are all monitored by an on-line PLC system. After molecular distillation, the product is sent for purity detection by NMR.

[0072] Coal gas membrane separation and chemical looping reforming system: A membrane separation device is used to test the purity of CH4 (target > 95%), and on-line gas flow and temperature monitoring instruments are equipped in the chemical looping reaction chamber.

[0073] Data acquisition: The temperature, pressure, time, reaction conversion rate, and product composition at each key step are all recorded by on-line instruments (sensors, PLC, on-line gas chromatography). Regular off-line samples are taken for qualitative and quantitative analysis of the product using GC-MS, HPLC, and NMR.

[0074] II. Process parameters and steps

[0075] Programmed temperature pyrolysis:

[0076] Parameters: The heating temperature gradient is 400–700 °C, and the holding time at each stage is 5 minutes.

[0077] Effect: The tar components are successfully adjusted, and the proportion of light aromatics reaches 62%, meeting the subsequent extraction requirements as detected by GC-MS.

[0078] Data acquisition description: The temperature curve is collected by a thermocouple, and the tar composition is quantitatively detected by off-line GC-MS.

[0079] Supercritical CO2 gradient extraction:

[0080] Parameters: The working pressure is set at 30 MPa, the temperature is 80 °C, and the extraction time is 30 minutes.

[0081] Formula application: The formula

[0082] E = (1 - e -α(P-Pmin) )·(1 - e -β(T-Tmin) )·(1 - e -γt )

[0083] After experimental correction, α = 0.10 MPa -1 、β = 0.08 °C -1 、γ = 0.05 min -1 , and the extraction efficiency is calculated to be approximately 0.94, corresponding to a light aromatic yield of over 92%.

[0084] Data acquisition description: Before and after extraction, on-line effluent samples are taken to monitor the change in aromatic content using GC-MS.

[0085] Microchannel directional catalytic oxidation:

[0086] Parameters: reaction temperature 220 °C, pressure 0.5 MPa, reaction residence time 1.2 h; oxygen concentration is regulated in a gradient manner, gradually increasing from 15% to 30%, according to the formula:

[0087] X = 1 - e-keffτ

[0088] keff = k0·f(O2) and

[0089] Set k0 = 0.80 h -1 、O2,crit = 20%, δ = 2%, and the calculated aromatics conversion rate X is approximately 0.87, that is, the conversion rate is 87%, and the oxalic acid selectivity detected by HPLC is 78%.

[0090] Data acquisition instructions: An on-line oxygen concentration sensor, temperature sensor, and flow rate sensor are installed in the microchannel; the reaction products are quantitatively analyzed by gas chromatography on-line.

[0091] Ultrasonic intensification of esterification reaction:

[0092] Parameters: Oxalic acid and methanol are mixed in a molar ratio of 1:4, a 40 kHz ultrasonic field is used, and the reaction time is 1.5 h.

[0093] Mass transfer enhancement relationship of ultrasonic intensification of esterification reaction:

[0094]

[0095] Among them, kL0 = 0.02 cm / s, P US = 0.5 W / cm 2 、P0 = 0.1 W / cm 2 、η = 0.30 are set. After calculation, the mass transfer coefficient is increased by about 50%, and the esterification rate is increased to 99.2%.

[0096] Data acquisition instructions: The temperature and amplitude during the reaction process are collected by on-line monitoring instruments, and the content of dimethyl oxalate in the final product is verified by HPLC.

[0097] Fixed-bed catalytic hydrogenation reaction:

[0098] Parameters: reaction temperature 200 °C, pressure 3.0 MPa, liquid hourly space velocity 0.8 h -1 ; The hydrogen supply is self-made hydrogen.

[0099] The crude ethylene glycol is purified by molecular distillation after hydrogenation, and the purity of ethylene glycol detected by NMR > 99.9%.

[0100] Among them, the reaction temperature and pressure of hydrogenation are recorded in real time by PLC, and the purity of the product is detected by off-line NMR.

[0101] Gas membrane separation and chemical-looping reforming for hydrogen supply:

[0102] After membrane separation, the purity of CH4 reaches 96%. The chemical looping reaction condition is steam reforming over the Fe2O3-CeO2 support, and the H2 / CO ratio is controlled at 2:1.

[0103] The self-made hydrogen meets the requirements of the hydrogenation reaction, and the overall energy consumption is reduced by about 35%.

[0104] Among them, the gas components in the membrane separation and reforming device are detected by on-line gas chromatography, and the reaction temperature and flow rate are monitored by PLC.

[0105] As can be seen from the above, the light aromatic hydrocarbon yield: the experimental group reaches about 94% (calculated value and verified by GC-MS), which is nearly 20 percentage points higher than the traditional method (about 75%).

[0106] The catalytic oxidation conversion rate: 87% in the experimental group, and the oxalic acid selectivity is 78%. The experimental data are better than those of the traditional high-pressure reactor (conversion rate about 80%, selectivity about 65%).

[0107] The esterification reaction time: the esterification rate reaches 99.2% within 1.5 hours, which is 62.5% shorter than the traditional 4-hour process, improving the reaction efficiency.

[0108] The purity of ethylene glycol: the product purity after the hydrogenation process > 99.9%, ensuring industrial-grade quality.

[0109] Energy utilization: The overall system energy consumption is 35% lower than the traditional process, and the self-supply of hydrogen realizes the closed-loop of energy and materials.

[0110] As can be seen from the above, through the front-end programmed temperature pyrolysis reaction, under the regulation of the temperature gradient and the assistance of the catalyst, the tar components in the coal pyrolysis products are reasonably distributed, rich in light aromatic hydrocarbons. Applying the supercritical CO2 dynamic extraction process, using the gradient regulation of pressure, temperature and time, the precise directional separation of light aromatic hydrocarbons in tar is realized. This method has advantages in both chemical phase equilibrium and mass transfer kinetics, and can overcome the problems of poor selectivity and solvent residue in traditional organic solvent extraction, providing high-purity raw materials for downstream reactions and reducing the interference of by-product impurities;

[0111] Using a microchannel reactor to achieve high-surface-area gas-solid contact, supplemented by a nanoscale catalyst and an oxygen concentration gradient control strategy, so that aromatic hydrocarbons are oxidatively oriented to generate the target oxalic acid, avoiding over-oxidation to generate useless by-products. Introducing an oxygen concentration dynamic regulation model to fundamentally adjust the reaction rate and selectivity, improve the conversion efficiency, and ensure the stability of the product molecular structure, which has significant theoretical advantages in the oxidation reaction;

[0112] In the esterification reaction, the ultrasonic field is utilized to enhance mass transfer, break the equilibrium limitation of the traditional esterification reaction, and enable the rapid mixing of molecules in the reaction system, thereby shortening the reaction time and improving the conversion efficiency. Under the action of the physical field, ultrasonic waves cause micro-scale cavitation effects and local high-temperature and high-pressure phenomena, which can effectively overcome the limitation of molecular diffusion, promote the reaction rate, and thus achieve high reaction conversion in a short time and reduce the reaction energy consumption.

[0113] Comparative example:

[0114] Traditional process description:

[0115] I. Overview of the traditional process flow:

[0116] Step 1: Tar extraction:

[0117] Conventional organic solvents are used to extract tar, and the extraction efficiency is about 70% - 75%, but the component selectivity is relatively poor.

[0118] Data collection: Offline GC-MS is used for component detection.

[0119] Step 2: Catalytic oxidation:

[0120] The reaction is carried out at normal pressure or slightly above normal pressure, the oxygen concentration control is not precise, the conversion rate of aromatic hydrocarbons is about 80%, and the selectivity of oxalic acid is about 65%.

[0121] Data collection: HPLC is used to detect products and by-products.

[0122] Step 3: Esterification reaction:

[0123] Without ultrasonic field assistance, the esterification reaction is carried out under normal temperature stirring conditions, the reaction time is about 4 hours, and the esterification rate is only about 85%.

[0124] Data collection: Online temperature and reaction time are recorded, and the product components are detected by GC.

[0125] Step 4: Catalytic hydrogenation:

[0126] Using externally purchased hydrogen supply, the fixed-bed hydrogenation reaction is carried out at 200 °C and 3.0 MPa, and the product purity is about 98% - 99%.

[0127] Data collection: Temperature, pressure are recorded, and the product after the reaction is detected by NMR.

[0128] Step 5: Hydrogen supply:

[0129] Externally purchase high-pressure hydrogen, without a self-supplying system, which increases the raw material transportation and storage costs.

[0130] II. Experimental parameters and data

[0131] Tar extraction:

[0132] Traditional parameters: The solvent extraction temperature is about 50°C, the time is 60 minutes, the extraction efficiency is 70%, and the relative yield of light aromatic hydrocarbons is 70% - 75%.

[0133] Data acquisition description: Offline GC-MS is used to detect the aromatic hydrocarbon content in the sample.

[0134] Catalytic oxidation:

[0135] Traditional parameters: The reaction temperature is 210°C, the pressure is 0.5 MPa, the oxygen concentration is fixed at 20%, the conversion rate is only 80%, and the oxalic acid selectivity is 65%.

[0136] Data acquisition description: HPLC is used to quantify the oxalic acid content and the by-product ratio.

[0137] Esterification reaction:

[0138] Traditional parameters: Without ultrasonic assistance, the reaction time is 4 hours, and the esterification rate is about 85%.

[0139] Data acquisition description: After sampling, the content of dimethyl oxalate is tested by GC.

[0140] Hydrogenation reaction and product purification:

[0141] Traditional parameters: The fixed-bed hydrogenation reaction conditions are similar to this scheme, but due to the influence of upstream products, there are more impurities in the crude ethylene glycol, and the purity after molecular distillation is about 98% - 99%.

[0142] Data acquisition description: The product purity is detected by NMR.

[0143] Energy and cost:

[0144] Traditional process: The overall energy consumption is relatively high, the proportion of external hydrogen supply is large, and there are raw material transportation and safety hazards.

[0145] Data acquisition description: The system energy consumption is statistically realized by an online energy meter and logistics records.

[0146] III. The technical effects of the comparative example and Example 1 are compared as shown in Table 1 below:

[0147] Table 1

[0148]

[0149]

[0150] IV. Description of data acquisition methods

[0151] Online monitoring: All reaction parameters (temperature, pressure, gas concentration, liquid hourly space velocity, etc.) are uploaded to the data acquisition platform in real time by the PLC and sensor system to ensure the continuity and accuracy of operation process data.

[0152] Offline analysis: The components and purity of the products at each key step are analyzed by GC-MS, HPLC, and NMR to ensure the correspondence between the data and the formula calculation.

[0153] Experimental design: Multiple groups of parallel experiments are designed to compare the key indicators obtained by using this solution and the traditional process under the same reaction conditions, and the average value and standard deviation are statistically analyzed to ensure that the data is statistically significant.

[0154] As can be seen from the above, through the comparison test data of Example 1 and the comparative example, it can be clearly proved that:

[0155] This solution adopts advanced control algorithms and process optimization measures in each process such as the extraction, catalytic oxidation, esterification, and hydrogenation of light aromatics, and finally realizes a significant improvement in the purity and yield of ethylene glycol products.

[0156] Process optimization not only shortens the reaction time (for example, the esterification time is shortened from 4 hours to 1.5 hours), but also reduces the overall energy consumption (reduced by about 35%), reduces the risk of external hydrogen supply, and realizes the self-sufficient cycle of internal energy in the system.

[0157] The data acquisition means are comprehensive and accurate, ensuring the reliability of the process model formula and the real-time monitoring accuracy, and providing solid data support and process control demonstration for future industrial scale-up.

[0158] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A new method for efficiently preparing ethylene glycol from by-products of coal pyrolysis, characterized in that, Including: Performing programmed temperature pyrolysis reaction on coal to obtain tar by-products rich in light aromatic hydrocarbons; Performing supercritical fluid extraction and separation on the tar by-products to obtain a high-purity light aromatic hydrocarbon mixture; Performing directional catalytic oxidation on the aromatic hydrocarbon mixture to obtain oxalic acid products; Reacting the oxalic acid product with an alcohol substance in an ultrasonic field through establishing a mass transfer enhancement model for ultrasonic enhanced esterification reaction to obtain oxalate products; Performing catalytic hydrogenation reaction on the oxalate products to obtain crude ethylene glycol products; Purifying the crude ethylene glycol products to obtain the target product ethylene glycol.

2. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 1, characterized in that, The supercritical fluid extraction method uses supercritical carbon dioxide as an extractant, and performs gradient separation on the tar by-products by adjusting the pressure range of 8 - 30 MPa and the temperature of 40 - 80 °C to obtain a light aromatic hydrocarbon mixture with a yield of not less than 92%.

3. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 2, characterized in that, The supercritical fluid extraction method realizes automatic control by real-time monitoring of pressure, temperature and time and cooperating with online data feedback. The calculation formula for the extraction efficiency E is: E = (1 - e -α(P-Pmin) )·(1 - e -β(T-Tmin) )·(1 - e -γt ) E: Extraction efficiency, representing the relative yield of selectively extracting light aromatic hydrocarbons from tar by-products; P: Operating pressure during extraction, unit: MPa; Pmin: The lowest pressure required to achieve preliminary effective extraction; T: Extraction temperature, unit: °C; Tmin: The lowest temperature at which effective dissolution and mass transfer start to occur; t: Supercritical extraction time; α, β, γ: Empirical constants, respectively reflecting the sensitivity of pressure, temperature and time to the extraction efficiency, determined by experimental calibration.

4. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 1, characterized in that, The directional catalytic oxidation uses a supported nano-catalyst containing CeO2-MoO3, performs a gas-solid phase reaction in a microchannel reactor, and adopts an oxygen concentration gradient catalytic oxidation reaction rate model to control the oxygen supply method with a gradient of oxygen concentration from 15% to 30%, so that the conversion rate of benzene aromatic hydrocarbons is higher than 85% and the selectivity of oxalic acid is higher than 78%.

5. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 4, characterized in that, The calculation formula for the oxygen concentration gradient catalytic oxidation reaction rate model is: X = 1 - e-keffτ keff = k0·f(O2) and Where, X: Reaction conversion rate, representing the proportion of light aromatic hydrocarbons converted to oxalic acid; τ: Reaction residence time; k0: Basic reaction rate constant, reflecting the reaction rate under standard oxygen concentration conditions; O2: Oxygen concentration in the reactor, regulated by gradient; O2,crit: Critical oxygen concentration, when exceeding this value, the reaction is prone to over-oxidation to generate CO2; δ: Slope parameter, used to describe the sensitivity of oxygen concentration to the reaction rate.

6. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 1, characterized in that, The esterification reaction uses an oxalic acid product and methanol mixed in a molar ratio of 1:4, uses an ionic liquid containing a sulfonic acid group as a catalyst, and uses an ultrasonic field with a frequency of 40 kHz to enhance the reaction, shortening the esterification reaction time to 1.5 hours and increasing the esterification rate to 99.2%.

7. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 1, characterized in that, The formula for the ultrasonic enhanced esterification reaction mass transfer enhancement model is: Or Where kL: Actual mass transfer coefficient, representing the enhancement effect of the ultrasonic field on the mass transfer rate; kL0: Benchmark mass transfer coefficient, the mass transfer rate under the condition of no ultrasonic field; PUS: Ultrasonic power density, unit: W / cm 2 , or the effective power of the ultrasonic field, whose value is related to the output power and frequency of the ultrasonic device; ξ, μ: Empirical parameters, respectively representing the intensity and response index of ultrasonic power on mass transfer enhancement, obtained by fitting experimental data; η: Enhancement factor, reflecting the logarithmic effect of the ultrasonic field on mass transfer enhancement; P0: Reference power density parameter.

8. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 1, characterized in that, The catalytic hydrogenation reaction uses a Cu / SiO2-Al2O3 catalyst and is carried out in a multi-stage fixed-bed reactor. The reaction temperature is 200 °C, the pressure is 3.0 MPa, and the liquid hourly space velocity is 0.8 h -1 , and the obtained crude ethylene glycol product has a purity of over 99.9% after subsequent treatment.

9. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 1, characterized in that, The gas produced during the coal pyrolysis process is subjected to membrane separation and purification to obtain methane with a purity higher than 95%, which is used for chemical looping reforming reaction to produce hydrogen, and the generated hydrogen is used in the catalytic hydrogenation reaction step. The chemical looping reaction uses Fe2O3-CeO2 as the oxygen carrier, and the volume fraction of H2 / CO is controlled to be 2:1 by adjusting the reaction conditions.

10. The new method for efficiently preparing ethylene glycol by using by-products of coal pyrolysis according to claim 9, characterized in that, The steam by-produced in the chemical looping reaction is introduced into the esterification reaction step after heat exchange and reused as a heat source to achieve the recycling of system energy.

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