Direct coal liquefaction residue pyrolysis viscosity reduction method based on inhibition-cracking-regulation triple synergistic system
By employing a triple synergistic system of inhibition-pyrolysis-regulation, and utilizing the synergistic effects of modifiers, nanocatalysts, and free radical terminators, the viscosity control problem in the pyrolysis process of coal direct liquefaction residue was solved, achieving efficient viscosity reduction and efficient recovery of high-value-added liquid products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-05
- Publication Date
- 2026-03-17
AI Technical Summary
Existing technologies are unable to effectively reduce the viscosity of coal direct liquefaction residue, leading to problems such as reactor blockage, reduced heat transfer efficiency, and equipment coking during pyrolysis. Furthermore, existing methods are not economically viable and may pose a risk of secondary coking.
A triple synergistic system of inhibition-cracking-regulation is adopted, in which a stable chemical bond structure is formed by a modifier, a nanoscale transition metal catalyst is used for mid-term catalytic cracking, and diphenyl disulfide is introduced as a free radical terminator in the viscosity peak temperature range to dynamically regulate the pyrolysis process.
It significantly reduces the viscosity of coal liquefaction residue during pyrolysis, increases the yield of liquid products and the proportion of light oil, reduces coke yield, and improves the economic efficiency and safety of the process.
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Figure CN121674099A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal chemical technology, specifically to a method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation. Background Technology
[0002] Direct coal liquefaction (DCL) is a key technological pathway for converting solid coal into clean liquid fuels and chemicals. However, this process inevitably generates a byproduct—direct coal liquefaction residue (DCLR)—accounting for approximately 20%–30% of the raw coal processing volume. DCLR is an extremely complex multiphase mixture, highly aromatic, rich in unreacted coal organic matter, asphaltene, preasphaltene, catalyst particles, and ash. The asphaltenes are large molecules composed of fused aromatic ring systems, containing numerous heteroatoms (O, N, S) and alkyl side chains. These molecules form strong non-covalent bonds through π-π stacking, hydrogen bonding, and acid-base interactions, creating a three-dimensional network structure. This complex chemical composition endows DCLR with a series of physicochemical properties unfavorable to subsequent processing, with its exceptionally high viscosity and complex rheological behavior being the most critical bottleneck. This high viscosity characteristic poses a significant challenge to the efficient utilization of DCLR in pipeline transportation, atomized feeding, and downstream processes such as pyrolysis, gasification, or coking.
[0003] When coal direct liquefaction residue is pyrolyzed to obtain fuel oil and chemicals, the aforementioned three-dimensional network structure undergoes a dramatic increase in viscosity due to thermal activation during the critical intermediate stage of thermal conversion at 300℃ to 400℃. This results in an order-of-magnitude jump in the system's viscosity, forming an extremely high "viscosity peak." This phenomenon triggers a series of serious engineering problems, including but not limited to: reactor and pipeline blockage, a sharp decline in heat transfer efficiency, overload of stirring torque, and interruption of continuous feeding systems. Consequently, it severely restricts the efficient and large-scale resource utilization of coal direct liquefaction residue.
[0004] Currently, existing technologies for addressing the high viscosity problem of coal direct liquefaction residue can be mainly divided into the following categories: (1) Physical dilution method: The most common method is to dilute the residue by mixing a large amount of hydrogen-donating solvent (such as tetrahydronaphthalene, diesel fraction) or low-value oil products. Although this method can temporarily reduce the initial viscosity, it is a physical means that "treats the symptoms but not the root cause". During the pyrolysis process, the diluent will preferentially vaporize, resulting in the viscosity problem of the system still existing in the critical temperature range, and the circulation and recovery of a large amount of solvent significantly increases operating costs and energy consumption. (2) Catalytic hydrocracking method: By using catalysts such as Co-Mo and Ni-Mo under high-pressure hydrogen atmosphere, the macromolecules in the residue are hydrocracking. This method is effective, but it faces harsh operating conditions (high-pressure hydrogen), expensive equipment investment, and problems such as the decrease in target liquid yield and the increase in gas yield due to excessive hydrogenation, resulting in poor economic efficiency. (3) High-temperature pyrolysis method: Simply relying on increasing the pyrolysis temperature to destroy the macromolecular structure. However, at high temperatures, the free radical condensation reaction and the cracking reaction compete with each other, which easily leads to secondary coking, generating more coke rather than liquid products. This not only reduces the liquid yield but also causes equipment coking and heat transfer surface contamination. (4) Surfactant dispersion method: Try to use conventional surfactants to improve the dispersibility of residues. However, ordinary surfactants have poor thermal stability and have already decomposed and become ineffective at pyrolysis temperature, so they cannot play a role in the viscosity peak temperature range.
[0005] The above methods all have obvious limitations, which shows that the existing technology needs further improvement. Summary of the Invention
[0006] The purpose of this invention is to provide a method for reducing the viscosity of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation, which can fundamentally solve the viscosity control problem in the pyrolysis process of coal direct liquefaction residue and simultaneously achieve efficient recovery of high-value-added liquid products.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation, comprising the following steps in sequence: a. Pretreatment: swelling the coal direct liquefaction residue to increase its surface area and active sites.
[0008] b. Inhibition-Cracking-Regulation, which includes the following sub-steps: b1. Adding a modifier to the pretreated coal direct liquefaction residue to react and form a stable chemical bond structure on the surface of the coal direct liquefaction residue; the modifier is maleic anhydride-grafted polypropylene or styrene-maleic anhydride copolymer.
[0009] b2. Add nanoscale transition metal catalyst to the modified residue obtained in step b1, disperse it under ultrasonic conditions, and then heat treat it to obtain sample one; b3. Add diphenyl disulfide to sample one and stir and mix it evenly at a certain temperature to obtain sample two.
[0010] c. Programmed temperature pyrolysis, which includes the following sub-steps: c1. Place sample 2 in a pyrolysis reactor and heat it to 300~360 ℃ under an inert atmosphere as the viscosity peak temperature window. Maintain the temperature for 10~30 min. During this stage, diphenyl disulfide decomposes into a free radical terminator, which actively intervenes at the molecular level and cuts off the free radical polycondensation path that leads to viscosity spikes and coking, thereby reducing viscosity.
[0011] c2. After the isothermal period, the temperature is increased to 500-550℃ at a rate of 5-10℃ / min for pyrolysis. The product is then collected.
[0012] The technical effects directly brought about by the above technical solution are as follows: First, by swelling the coal liquefaction residue, a large number of hydroxyl (-OH) and carboxyl (-COOH) groups are present on the surface of the swollen coal liquefaction residue. Then, a modifier is added to the swollen coal liquefaction residue to react and form a stable chemical bond structure on the surface of the coal direct liquefaction residue. The modifier is selected as maleic anhydride-grafted polypropylene or styrene-maleic anhydride copolymer. The maleic anhydride groups in the modifier can undergo esterification or hydrogen bonding with the groups on the surface of the coal liquefaction residue to form a stable chemical bond structure (i.e., "front-end prevention"). A nanoscale transition metal catalyst is added to the modified residue. The nanoscale transition metal catalyst realizes the catalytic cracking of the macromolecular network in the mid-temperature zone of pyrolysis (i.e., "mid-terminal bond breaking"). The thermally triggered reversible crosslinking agent realizes the dynamic control of the free radical reaction path in the viscosity peak temperature zone (i.e., "end-end control"). The three work together to form an intelligent viscosity reduction system that dynamically responds to the pyrolysis process.
[0013] The above-mentioned method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-cracking-regulation, in step a, involves mixing and stirring the coal direct liquefaction residue with a low-molecular-weight aromatic solvent at a mass ratio of 1:0.2-0.8 at 50-80°C for 40-60 minutes to induce swelling; the low-molecular-weight aromatic solvent is selected from at least one of toluene, xylene, and tetrahydronaphthalene.
[0014] In the above-mentioned method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-cracking-regulation, in step b1, the amount of modifier added is 1-3% of the dry basis mass of the coal direct liquefaction residue. After adding the modifier, the reaction is carried out for 30-60 minutes, and then the low molecular weight aromatic solvent is removed by vacuum distillation under the conditions of 60-80℃ and -0.1--0.09 MPa.
[0015] In the above-mentioned method for reducing viscosity of coal direct liquefaction residue by pyrolysis based on a triple synergistic system of inhibition-pyrolysis-regulation, in step b1, the grafting rate of the modifier on the surface of the pretreated coal liquefaction residue is 0.8 to 1.5%.
[0016] In the above-mentioned method for reducing viscosity of coal direct liquefaction residue by pyrolysis based on a triple synergistic system of inhibition-cracking-regulation, in step b2, the nanoscale transition metal catalyst is a supported bimetallic catalyst, the active component of which is selected from Ni-Mo, Co-Mo or Ni-W, and the total loading of the active component is 15~25wt% based on oxides, and the support is γ-Al2O3 or SiO2; the specific surface area of the nanoscale transition metal catalyst is 200~350 m² / g, the average pore size is 5~15 nm, and the particle size distribution is 20~100 nm.
[0017] The above-mentioned method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation uses Ni-Mo / γ-Al2O3 nanocatalyst as the supported bimetallic catalyst.
[0018] In the above-mentioned method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation, in step b3, diphenyl disulfide is used as a thermally triggered reversible crosslinking agent, and its addition amount is 0.5-2% of the mass of sample one. The mixture is mechanically stirred and mixed for 10-20 minutes at a temperature of 60-80℃ until homogeneous.
[0019] In the above-mentioned method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation, in step c, the pyrolysis process is carried out in a fixed-bed reactor or a high-pressure autoclave rheometer, with nitrogen or argon as the inert atmosphere and a gas flow rate of 50~200 mL / min.
[0020] The above-mentioned method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation involves heating to 340~350 ℃ as the peak viscosity temperature window and maintaining the temperature constant for 15~20 min.
[0021] The above-mentioned method for reducing viscosity by pyrolysis of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation includes the following steps: in step b2, the ultrasonic power is 300-500W and the time is 10-20min. The heat treatment step includes: under nitrogen protection, heat treatment at 100-120℃ for 1-2h to uniformly disperse the nanoscale transition metal catalyst in the modified residue.
[0022] Compared with the prior art, the present invention brings the following beneficial technical effects:
[0023] (1) Breakthrough effect in viscosity reduction: After being treated by the method of the present invention, the apparent peak viscosity of coal liquefaction residue during the pyrolysis process can be reduced from 5000-8000 mPa·s to 800-2000 mPa·s, with a reduction of up to 70%~85%, and the viscosity curve is smooth without drastic fluctuations.
[0024] (2) Product yield and quality are significantly improved: the yield of liquid phase products can be increased from 40-50 wt% to 55-65 wt%, an increase of 20-35%. At the same time, due to the selective catalytic effect of nanoscale transition metal catalysts, the proportion of light oil (boiling point <360℃) is significantly increased.
[0025] (3) The coking rate is significantly reduced: by inhibiting free radical polycondensation, the coke yield is reduced by 15-30%, which prolongs the equipment operation cycle.
[0026] (4) High process economy and safety: The method is carried out at atmospheric pressure and medium and low temperature modification stage, avoiding high pressure hydrogen environment, most solvents can be recovered, functional additives are used in small amounts, and the overall energy consumption and operating cost are significantly lower than those of catalytic hydrogenation and other technical routes, which have strong prospects for industrial application. Attached Figure Description
[0027] Figure 1 This is a flowchart of a process for reducing the viscosity of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation.
[0028] Figure 2 This is a schematic diagram of the triple synergistic viscosity reduction mechanism of inhibition-pyrolysis-regulation in this invention.
[0029] Figure 3 This is a comparison chart of the viscosity-temperature curves of the embodiments and comparative examples of the present invention during the pyrolysis process.
[0030] Figure 4 This is a comparison diagram of the pyrolysis product distribution between the embodiments and the comparative examples of the present invention. Detailed Implementation
[0031] This invention proposes a method for reducing the viscosity of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation. To make the advantages and technical solutions of this invention clearer and more explicit, the invention will be further described below with reference to specific embodiments.
[0032] All the raw materials mentioned in this invention can be purchased through commercial channels.
[0033] Raw materials: Shenhua Coal Direct Liquefaction Residue (DCLR), industrial sample, pulverized to 100 mesh, air-dried basis moisture (Mad) < 1%; Solvents: Toluene, tetrahydronaphthalene, analytical grade; Modifiers: Maleic anhydride-grafted polypropylene (MAH-g-PP, grafting rate 1.0%), styrene-maleic anhydride copolymer (SMA). Catalyst: Commercial Ni-Mo / γ-Al2O3 catalyst (NiO: 4wt%, MoO3: 18wt%, specific surface area 280 m²). 2 / g, average particle size ~40nm); commercial nano MoO3 powder. Thermally triggered reversible crosslinking additive: diphenyl disulfide (DPDS), chemically pure.
[0034] Instruments: Autoclave pyrolysis reactor with online viscometer, ultrasonic cell disruptor, vacuum drying oven.
[0035] The core concept of this invention lies in constructing a triple endogenous synergistic system of inhibition-pyrolysis-regulation, which achieves dynamic regulation of the pyrolysis process of coal liquefaction residue. This system first utilizes a modifier for front-end prevention, inhibiting the formation of large molecular networks; then, it uses a nanoscale transition metal catalyst to catalyze the pyrolysis of heavy components in the middle stage; finally, it introduces diphenyl disulfide, which automatically decomposes into a free radical terminator at the viscosity peak temperature window, actively intervening at the molecular level and cutting off the free radical condensation pathways that lead to viscosity spikes and coking. This significantly reduces viscosity (by 70-85%) while simultaneously increasing the yield of light oil (by 20-35%), overcoming the technical challenge of existing technologies that cannot simultaneously achieve viscosity reduction and quality improvement.
[0036] like Figure 2 As shown, this invention employs a triple synergistic system of inhibition-pyrolysis-regulation to reduce the viscosity of coal direct liquefaction residue. Specifically, chemical modification (prevention) is responsible for front-end prevention, reversible crosslinking (control) is responsible for mid-stage regulation, and nanocatalysis (treatment) is responsible for back-end bond breaking, covering the entire pyrolysis process. The decomposition products of diphenyl disulfide and the catalytic active sites of the nanoscale transition metal catalyst converge in the viscosity peak temperature range. The small-molecule free radical terminator generated by the decomposition of the crosslinking agent provides a "quenching channel" for the large-molecule free radicals generated by catalyst pyrolysis, changing the reaction path of free radicals inevitably heading towards condensation polymerization during simple pyrolysis. This achieves good synergy between the pyrolysis reaction and the stabilization reaction, effectively inhibiting condensation polymerization and coking.
[0037] To fully illustrate the technical effects of the present invention, a series of embodiments and comparative examples are presented below for detailed comparison. All experiments used the same batch of Shenhua Coal Direct Liquefaction Residue (DCLR) as raw material, and its industrial analysis and elemental analysis are shown in Table 1.
[0038] Raw materials: Coal direct liquefaction residue: provided by Shenhua Group, crushed and passed through a 100-mesh sieve, dried in a vacuum drying oven at 105℃ for 24 hours to constant weight (mass change <0.1%), and then sealed and stored in a desiccator.
[0039] Table 1. Basic Properties of Direct Coal Liquefaction Residue (DCLR)
[0040]
[0041] Main reagents: Dispersing solvents: toluene (analytical grade, Sinopharm Group); tetrahydronaphthalene (chemically pure, TCI).
[0042] Polymer modifiers: maleic anhydride-grafted polypropylene (MAH-g-PP, grafting rate 1.2%, Nanjing Suershu); styrene-maleic anhydride copolymer (SMA, Sigma-Aldrich).
[0043] Nanocatalyst: Ni-Mo / γ-Al₂O₃. Prepared by an equal-volume impregnation method, loading nickel nitrate and ammonium molybdate solutions onto a γ-Al₂O₃ support, followed by drying at 120℃, calcination at 500℃ for 4 h, and reduction with H₂ at 500℃ for 3 h. Physical properties: NiO = 4.0 wt%, MoO₃ = 18.0 wt%, BET specific surface area = 285 m². 2 / g, average pore size = 8.5 nm, average particle size = 40 nm.
[0044] Fe-Co / activated carbon: Commercially available, specific surface area >500 m² 2 / g.
[0045] Thermally triggered reversible crosslinking agents: diphenyl disulfide (DPDS, purity >98%, TCI); 2,2'-dihydroxydiethyl phthalate (DHP, purity >95%, TCI).
[0046] Comparative catalyst: Industrial-grade Ni-Mo / γ-Al2O3 catalyst (particle size distribution 10-50 μm).
[0047] Unified analysis and evaluation methods: Viscosity measurement: In an autoclave rheometer under N2 atmosphere, at a constant shear rate of 10 s⁻¹. -1 The temperature is increased in a programmed manner, and the apparent viscosity is recorded in real time.
[0048] Product yield calculation: After pyrolysis, weigh and calculate the yield of each product.
[0049] Liquid phase yield (wt%) = (mass of condensed oil + mass of water) / mass of feed to dry DCLR × 100%.
[0050] Coke yield (wt%) = (mass of solid residue in reactor - mass of ash) / mass of feed to dry DCLR × 100%.
[0051] Gas yield (wt%) = 100% - liquid phase yield - coke yield.
[0052] Light oil analysis: The liquid phase product was separated into light oil (boiling point <360°C) and heavy oil by simulated distillation gas chromatography (ASTM D2887).
[0053] The present invention will be further described below with reference to specific embodiments.
[0054] Example 1: A method for reducing the viscosity of direct coal liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation, comprising the following steps: Step 1, swelling: Accurately weigh 100.00 g of dried DCLR into a 500 mL three-necked flask. Add 40.00 g of toluene (mass ratio 1:0.4). Place in an oil bath at 70±1℃ and mechanically stir at 300 rpm for 50 min. The swelling effect is to allow solvent molecules to fully penetrate into the interior of the direct coal liquefaction residue, breaking its physical entanglement.
[0055] Step 2: Slowly inject 10 mL of a toluene solution of MAH-g-PP (concentration 0.2 g / mL, i.e., containing 2.000 g of MAH-g-PP) using a micro-injection pump. Maintain the reaction temperature at 70±1℃ and 300 rpm for a precise 40 min. Transfer the solution to a rotary evaporator, heat in a 75℃ water bath, and distill at -0.095 MPa for 30 min to recover the toluene, yielding the modified residue. This modifier achieves its modification by grafting its anhydride groups onto the polar groups in the swollen coal direct liquefaction residue, or by adsorbing onto aromatic sheets through π-π stacking, thereby constructing a steric hindrance layer on the surface of the residue macromolecules and inhibiting their reassociation tendency during the heating process from the source.
[0056] The modified residue was initially mixed with 1.500 g of Ni-Mo / γ-Al2O3 nanocatalyst (1.5 wt% of DCLR) in a mortar. The mixture was transferred to a 50 mL beaker and moistened with 5 mL of toluene. The beaker was placed in an ice-water bath. Ultrasonic treatment with a power of 400 W was applied intermittently for 15 min to ensure uniform dispersion, with the probe insertion depth kept constant. Ultrasonic-assisted dispersion was used to ensure that the Ni-Mo / γ-Al2O3 nanocatalyst achieved nanoscale uniform dispersion in the modified coal direct liquefaction residue. The mixture was then spread evenly in a crucible and placed in a tube furnace. The temperature was programmed to rise to 110 °C at a N2 flow rate of 100 mL / min and maintained at this temperature for 90 min to remove residual solvent and enhance the bonding between the catalyst and the residue matrix, yielding Sample 1. This step aims to pre-implant highly efficient cleavage active sites above the viscosity peak temperature range, preparing for subsequent targeted catalytic bond breaking.
[0057] Sample 1 was transferred to a small mixer, and 1.000 g of DPDS (1.0 wt% of DCLR) was added. The mixture was mechanically mixed at 60 rpm for 20 min on an 80°C hot plate to obtain Sample 2. This DPDS is a small molecule compound containing dynamic covalent bonds (preferably disulfide bonds -SS- or groups that can be reversibly broken via the Diels-Alder reaction). Its trigger decomposition temperature was precisely designed within the viscosity peak range of the residue (280~380°C). The mechanism of action of DPDS is dual: in the early stages of pyrolysis, it can act as a weak crosslinking point to moderately improve the system's dispersibility; when the temperature rises to its trigger temperature, the bonds break to generate active small molecule fragments (such as sulfur free radicals). These fragments can act as both hydrogen sources and free radical terminators, effectively quenching the large molecular free radicals generated by cracking, thus playing a dual role of "network dismantling" and "inhibiting polycondensation" at the "critical moment" when viscosity is about to surge.
[0058] Step 3: Accurately weigh 20.00 g of Sample 2 and place it into the rheometer measuring cup. Purge with N2 (50 mL / min) for at least 30 min to remove air. Under a 1.0 MPa N2 atmosphere (this back pressure is set to prevent premature vaporization of the solvent at low temperatures and is not a necessary condition), increase the temperature from 30 °C at 8 °C / min. When 340 °C is reached, the isothermal program is automatically triggered and held precisely for 20.0 min. After isothermal treatment, continue to increase the temperature to 550 °C at 8 °C / min and hold for 10.0 min. Record data in real time, and collect the product after completion.
[0059] This invention establishes a constant-temperature plateau of 10-30 minutes within a temperature range of 300-360℃. This plateau period represents the synergistic window between the decomposition of the reversible crosslinking agent and the initial activation of the nanocatalyst. During this stage, a triple mechanism works synergistically to ensure a smooth transition in system viscosity, preventing drastic peaks.
[0060] According to Example 1, through the three-dimensional synergistic effect of hierarchical dispersion grafting modification, in-situ pyrolysis by nanocatalysis and thermally triggered dynamic covalent bond dissociation, the apparent peak viscosity of the coal direct liquefaction residue pyrolysis system decreased from 5800 mPa·s to 950 mPa·s (a decrease of 83.6%), and the yield of liquid phase products increased to 62.5 wt%, of which light fraction accounted for 68.0%, achieving effective suppression of free radical condensation pathway and synergistic optimization of product distribution.
[0061] Example 2: A method for reducing the viscosity of coal direct liquefaction residue based on a triple synergistic system of inhibition-pyrolysis-regulation, comprising the following steps: Step 1, swelling: Accurately weigh 100.00 g of dried DCLR into a 500 mL three-necked flask. Add 40.00 g of tetrahydronaphthalene (mass ratio 1:0.6). Place in an 80℃ oil bath and mechanically stir at 300 rpm for 40 min.
[0062] Step 2: Add 1.500 g SMA and react for 60 min. Maintain 70±1℃ and 300 rpm for a precise reaction time of 40 min. Transfer to a rotary evaporator and distill at -0.095 MPa for 30 min in a 75℃ water bath to recover tetrahydronaphthalene and obtain the modified residue.
[0063] The modified residue was mixed with 2.000 g Fe-Co / activated carbon catalyst (2.0 wt%), ultrasonically dispersed (450 W, 20 min), and heat-treated at 105 °C for 120 min under N2.
[0064] The remaining steps are the same as in Example 1.
[0065] Example 3: The difference from Example 1 is that in step two, sample one is transferred to a small mixer and 0.500g of DPDS (0.5wt%) is added. In step three, when the temperature reaches 340℃, the isothermal program is automatically triggered and maintained precisely for 20.0min.
[0066] The remaining steps are the same as in Example 1.
[0067] Example 4: The difference from Example 1 is that in step two, sample one is transferred to a small mixer and 1.200 g of DHP (1.2 wt%) is added.
[0068] The remaining steps are the same as in Example 1.
[0069] Comparative Example 1: Blank control experiment. 100.00g of raw DCLR was taken and subjected to programmed temperature pyrolysis without any pretreatment, following step three of Example 1.
[0070] Comparative Example 2: Lacking a thermal triggering mechanism, the difference from Example 1 is that after obtaining Sample 1 in step 2, the programmed temperature rise is directly performed, i.e., the operation in step 3, without introducing diphenyl disulfide.
[0071] Comparative Example 3: Lacking a nanocatalytic mechanism, the difference from Example 1 is that the modified residue does not undergo nanocatalysis, and the modified residue is directly subjected to programmed temperature rise after the addition of diphenyl disulfide, i.e., step three.
[0072] Comparative Example 4: Using a micron-sized catalyst
[0073] The steps are the same as in Example 1, but in step two, the nano-Ni-Mo / γ-Al2O3 catalyst is replaced with an equal mass of industrial-grade Ni-Mo / γ-Al2O3 catalyst with an average particle size >10μm.
[0074] Comparative Example 5: Treatment with a single thermally triggered reversible crosslinking additive, without swelling, modification, or addition of nano-catalysts, directly adding 1.000g of DPDS to 100.00g of raw DCLR, and mechanically mixing at 80℃ for 20min.
[0075] Comparative Example 6: Traditional solvent dilution method. Treatment: 100.00g of raw DCLR and 40.00g of tetrahydronaphthalene were simply mechanically mixed at 70°C for 30min without any chemical reaction, catalyst addition, or solvent removal. This mixture was then directly pyrolyzed, following the same pyrolysis process as step three of Example 1.
[0076] As shown in Comparative Examples 1-6, neither a single technical approach (such as physical dilution alone, or the use of only thermally triggered reversible crosslinking additives or micron-sized catalysts) nor the absence of any functional unit (such as the absence of a thermal triggering mechanism or a nano-catalytic mechanism) can achieve the optimal viscosity reduction and quality improvement effects. This fully demonstrates that the "hierarchical dispersion modification-nano-catalytic pyrolysis-thermally triggered reversible crosslinking" triple synergistic system constructed in this invention is an organic whole. The three components are sequentially connected and functionally complementary, producing a synergistic effect of "1+1+1 > 3". This represents a key technological breakthrough for achieving efficient and high-value conversion of coal liquefaction residue.
[0077] The final viscosity test data of the above embodiments and comparative examples are compared and obtained in the following table, as shown in Table 2.
[0078] Table 2
[0079] serial number Solution Description Peak viscosity (mPa·s) Decrease (vs. Comparative Example 1) Liquid phase yield (wt%) Light oil yield (wt%) Coke yield (wt%) Example 1 Ni-Mo nanocatalyst + MAH-g-PP + DPDS (optimal) 950 83.60% 62.5 68 18.2 Example 2 Fe-Co / AC + SMA + Tetrahydronaphthalene 1100 81.00% 60.8 65.5 19.5 Example 3 Low-dose DPDS (0.5%) & high isothermal point 1500 74.10% 59.5 64 20.8 Example 4 Ester bond type thermally triggered reversible crosslinking additive (DHP) 1350 76.70% 60.2 66.5 20.5 Comparative Example 1 Blank control (unprocessed) 5800 - 45.8 55 32.5 Comparative Example 2 Lack of thermally triggered reversible crosslinking additives 3100 46.60% 58 63.8 23.8 Comparative Example 3 Missing nanocatalysts 1650 71.60% 54.5 62.5 25.1 Comparative Example 4 Using micron-scale catalysts 2800 51.70% 56 61 24 Comparative Example 5 Single thermally triggered reversible crosslinking additive treatment 4200 27.60% 48.5 58 30.1 Comparative Example 6 Traditional solvent dilution method 3500 39.70% 53.5 - 26.5
[0080] Note: The liquid phase yield of Comparative Example 6 includes unreacted diluent, and the actual conversion rate is lower.
[0081] The viscosity-temperature curves of the embodiments and comparative examples of the present invention during the pyrolysis process are shown in the figure below. Figure 3 As shown in the figure, the distribution of pyrolysis products in the embodiments of the present invention and the comparative examples are compared. Figure 4 As shown in the figure. This invention achieves a qualitative leap in technical performance by constructing a triple synergistic system of "hierarchical dispersion modification - nanocatalytic pyrolysis - thermally triggered reversible crosslinking": the method of this invention reduces the peak viscosity of coal liquefaction residue pyrolysis by 83.6% to 950 mPa·s, while increasing the liquid phase yield by 16.7 percentage points to 62.5 wt%. This synergistic effect has been proven to be the only path to achieve efficient viscosity reduction and product optimization, and its three functional units are indispensable. Compared with the limitations of physical dilution in traditional solvent dilution methods (Comparative Example 6), this invention achieves a paradigm shift from physical dilution to chemical modification and dynamic covalent chemical regulation; and the comparison with micron-scale catalysts (Comparative Example 4) confirms that nanoscale effects and uniform dispersion are key prerequisites for achieving efficient synergy. More importantly, the system exhibits excellent robustness and universality, maintaining stable and excellent performance even when the type of functional component is changed (such as SMA replacing MAH-g-PP) or key parameters are adjusted (such as the dosage of thermally triggered reversible crosslinking additives), demonstrating its great potential for industrial application.
[0082] Any parts not mentioned in this invention can be achieved by referring to existing technologies.
[0083] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.
Claims
1. A coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system, characterized in that, Comprise the following steps in sequence: a. Pretreatment: swelling of the coal direct liquefaction residue to increase its surface area and active sites; b. Inhibition-cracking-regulation, comprising the following sub-steps respectively: b1. Adding a modifier to the pretreated coal direct liquefaction residue for reaction and forming a stable chemical bonding structure on the surface of the coal direct liquefaction residue; the modifier is maleic anhydride grafted polypropylene or styrene-maleic anhydride copolymer; b2. Adding a nano-scale transition metal catalyst to the modified residue obtained in step b1, dispersing under ultrasonic conditions, and then heat treating to obtain sample one; b3. Adding diphenyl disulfide to the sample one and stirring uniformly at a certain temperature to obtain sample two; c. Temperature programmed pyrolysis, comprising the following sub-steps respectively: c1. Placing the sample two in a pyrolysis reactor, heating to 300-360 ℃ as a viscosity peak temperature window under an inert atmosphere, and keeping constant temperature for 10-30 min; the diphenyl disulfide is decomposed into a free radical terminator in this stage, which actively intervenes and cuts off the free radical polycondensation path leading to viscosity surge and coking from the molecular level and reduces the viscosity; c2. After constant temperature, heating to 500-550 ℃ at a rate of 5-10 ℃ / min for pyrolysis, and collecting the product after the end of pyrolysis.
2. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 1, characterized in that: In step a, the coal direct liquefaction residue and the low molecular aromatic hydrocarbon solvent are mixed and stirred at 50-80 ℃ for 40-60 min for swelling according to a mass ratio of 1:0.2-0.8; the low molecular aromatic hydrocarbon solvent is selected from at least one of toluene, xylene and tetralin.
3. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 1, characterized in that: In step b1, the amount of the modifier added is 1-3% of the dry basis mass of the coal direct liquefaction residue; after adding the modifier, the reaction is carried out for 30-60 min, and then the low molecular aromatic hydrocarbon solvent is removed by vacuum distillation under the conditions of 60-80 ℃ and -0.1 to -0.09 MPa.
4. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 3, characterized in that: In step b1, the grafting rate of the modifier on the surface of the pretreated coal liquefaction residue is 0.8-1.5%.
5. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 1, characterized in that: In step b2, the nano-scale transition metal catalyst is a supported bimetallic catalyst, the active component of which is selected from Ni-Mo, Co-Mo or Ni-W, and the total loading of the active component is 15-25 wt% in terms of oxide; the support is γ-Al2O3 or SiO2; the specific surface area of the nano-scale transition metal catalyst is 200-350 m² / g, the average pore size is 5-15 nm, and the particle size distribution is 20-100 nm.
6. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 5, characterized in that: The supported bimetallic catalyst is a Ni-Mo / γ-Al2O3 nano catalyst.
7. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 1, characterized in that: In step b3, diphenyl disulfide is used as a heat-triggered reversible crosslinking agent, and the amount added is 0.5-2% of the mass of sample one; the mixture is uniformly mixed by mechanical stirring at a temperature of 60-80 ℃ for 10-20 min.
8. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 1, characterized in that: In step c, the pyrolysis process is carried out in a fixed bed reactor or a high-pressure autoclave rheometer, the inert atmosphere is nitrogen or argon, and the gas flow rate is 50-200 mL / min.
9. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 7, characterized in that: Heating to 340-350 ℃ as a viscosity peak temperature window, and keeping constant temperature for 15-20 min.
10. The coal direct liquefaction residue viscosity reduction method based on the inhibition-cleavage-regulation triple synergistic system according to claim 1, characterized in that: In step b2, the ultrasonic power is 300-500 W, the time is 10-20 min, and the heat treatment step includes: heat treatment at 100-120 ℃ for 1-2 h under nitrogen protection to make the nanoscale transition metal catalyst uniformly dispersed in the modified residue.