A method for synthesizing chemicals based on co-pyrolysis of organic solid waste

Abstract

The application belongs to the technical field of organic compounds, and discloses a chemical synthesis method based on organic solid waste co-pyrolysis, which comprises the following steps: S1, screening organic solid waste, taking components with semi-crystalline and / or amorphous characteristics in the organic solid waste as A components, taking components with high crystallinity characteristics in the organic solid waste as B components, uniformly mixing the A components and the B components to obtain a mixture; S2, heating the mixture in an inert atmosphere to T1, and reacting the A components and the B components; S3, rapidly increasing the temperature to T2 under the condition of inert carrier gas purging, and then rapidly cooling the generated gas phase product to obtain a product. The application recombines the high crystalline components and the heterogeneous core, significantly improves the yield and quality of the target product through kinetic truncation, effectively avoids the secondary cracking of the high-value intermediates, reduces the yield of the gas by-products by 15-25%, and increases the selectivity of the light components in the liquid oil by more than 40%.

Description

Technical Field

[0001] This invention belongs to the field of organic compound technology, specifically relating to a chemical synthesis method based on cross-boundary induction and kinetic interception of co-pyrolysis of organic solid waste. Background Technology

[0002] With social development, the treatment of organic waste such as municipal solid waste and industrial solid waste has become an issue that cannot be ignored. Existing pyrolysis resource recovery technologies for these organic solid wastes generally focus on the mixed pyrolysis of biomass components and polymeric wastes (such as polyolefins, polyesters, and halogenated plastics). Specifically, slow pyrolysis is typically carried out at 500℃, or staged treatment is performed within a wide temperature range of 350–700℃. The technical principle of this pyrolysis treatment is mainly based on the free radical mechanism and hydrogen donation effect. That is, the high effective hydrogen-to-carbon ratio of polymeric wastes is used as a hydrogen donor, interacting with oxygen-containing free radicals released from biomass components to reduce the oxygen content of the pyrolysis oil and increase its calorific value; or the furan compounds produced by biomass pyrolysis react with the light olefins produced by polymeric pyrolysis. The Alder reaction produces monocyclic aromatic hydrocarbons.

[0003] Existing co-pyrolysis technologies for organic solid waste have the following problems: 1. The reaction path lacks directional control, resulting in extremely low yields of high-value intermediates. This is because existing processes lack precise segmentation of the reaction timescale and kinetic interception mechanisms. Primary intermediates generated during the reaction have a long residence time in the high-temperature zone, making them prone to secondary cracking or condensation. Therefore, the reaction usually proceeds along a thermodynamic steady-state path, and the products are mostly complex mixed pyrolysis oils, small-molecule gases, or low-value coke (e.g., the residual char rate of solid waste rich in polyester is as high as 32 wt% after pyrolysis alone), making it difficult to achieve efficient enrichment of specific metastable oxygen-containing and / or nitrogen-containing heterocyclic compounds. 2. The synergistic effect between heterogeneous components is uncontrollable. Due to the significant differences in pyrolysis temperature and phase evolution of different morphological components (e.g., some polymers decompose and deposit before biomass, while some highly crystalline components decompose after biomass), the physical compatibility is poor during mixed pyrolysis. Molten high-viscosity materials easily encapsulate biomass components, inhibit fluidization, clog pipelines, and cause coking in the reactor, often leading to equipment failure and thus reducing product quality and equipment lifespan. Furthermore, hydrogen halides released from halogenated solid wastes such as PVC can cause equipment corrosion and lead to excessive halogen content in pyrolysis oil, resulting in organic halide pollution. Thirdly, the products are highly uncertain, of low quality, and have high subsequent separation costs. The diverse raw materials for co-pyrolysis lead to extremely unstable reaction effects. The products have high oxygen content and low calorific value. Even with the use of catalysts, deactivation can easily increase operating costs. Conventional simple mixing cannot fundamentally break down the original solid / molten phase degradation barriers of each component. Relying solely on shallow free radical transfer is insufficient to achieve deep chemical reconstruction, resulting in numerous side reactions.

[0004] Therefore, it is necessary to propose a new pyrolysis treatment technology to overcome the technical obstacles of the existing organic solid waste co-pyrolysis technology, which suffers from extremely low yield of high-value intermediates due to thermodynamic equilibrium limitations and improper control of spatiotemporal scale. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a chemical synthesis method based on the co-pyrolysis of organic solid waste, which enables highly crystalline components to recombine with heterogeneous cores, significantly improves the yield and quality of target products through kinetic truncation, effectively avoids secondary cracking of high-value intermediates, reduces the yield of gaseous byproducts by 15-25%, and increases the selectivity of light components in liquid oil by more than 40%.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: A chemical synthesis method based on the co-pyrolysis of organic solid waste includes the following steps: S1. Screen the organic solid waste, take the component with semi-crystalline and / or amorphous characteristics as component A, take the component with high crystallinity characteristics as component B, mix component A and component B evenly to obtain a mixture. S2. The mixture is heated to T1 in an inert atmosphere, wherein T1 > the final melting temperature of component A, the initial melting temperature of component B ≤ T1 < the characteristic depolymerization temperature of component B, and component A reacts with component B. S3. Under the condition of purging with inert carrier gas, the temperature is rapidly increased to T2, which is the product generation temperature. Then, the generated gaseous product is rapidly cooled to obtain the product.

[0007] Preferably, in step S1, the mass ratio of component A to component B is (1:9) to (9:1).

[0008] Preferably, in step S2, T1 is 250–380°C.

[0009] Preferably, in step S3, T2 is 500–750°C.

[0010] Preferably, in step S3, the residence time of the generated gaseous product at T2 is τ, where τ is 0.5 to 5 s.

[0011] Preferably, in step S3, the cooling temperature is < -44°C.

[0012] Preferably, the initial melting temperature of component A is ≥60℃.

[0013] More preferably, component A includes one or more of the following: organic solid waste containing oxyanhydrides and / or esters, organic solid waste containing benzene rings and / or benzyl groups, organic solid waste containing nitrogen free radicals, and organic solid waste containing conjugated double bonds.

[0014] Preferably, the melting point of component B is >180℃.

[0015] More preferably, component B includes one or both of organic solid waste containing linear aliphatic polyamide and highly crystalline polyolefin organic solid waste.

[0016] Beneficial effects: This invention overcomes thermodynamic limitations to achieve unconventional product enrichment: through "cross-boundary induction," highly crystalline components are forced to deviate from their optimal depolymerization path (e.g., to avoid generating large amounts of caprolactam monomers) and instead recombine with heterogeneous cores. Compared to conventional co-pyrolysis without induction, the area ratio of target metastable intermediates (such as imides and alkyl aromatics) in the liquid-phase product can be increased from less than 10% conventionally to over 60% (up to over 70%).

[0017] This invention significantly improves the yield and quality of the target product through kinetic interception: by using rapid carrier gas purging combined with rapid condensation, "kinetic interception" effectively avoids secondary cracking of high-value intermediates, reducing the yield of gaseous byproducts by 15-25%, and reducing the yield of light components (C6) in liquid oil. C12) selectivity is increased by more than 40%.

[0018] The present invention has significant economic and environmental benefits: it does not require the addition of expensive catalysts, but only utilizes the physicochemical synergy between the multiphase components of organic solid waste to achieve directional conversion, which greatly reduces operating costs; at the same time, it converts low-value solid waste into high-value-added fine chemical raw materials, realizing an efficient closed loop of carbon and nitrogen resources. Attached Figure Description

[0019] Figure 1 The diagram shows one of the reaction systems applicable to this invention.

[0020] Figure 2 The GCMS spectra of the products of Examples 1 and 2 are shown. The high-value imide derivatives are located in the range of 18 to 21 min.

[0021] Figure 3 The figure shows the product distribution of component A in the separate pyrolysis of the embodiment and comparative example in stages. The peak accumulation in the figure represents the DTG curve of the thermogravimetric curve. The three fitting peaks are each curve separated from the DTG curve using the Gaussian model, which can be regarded as a degradation process of a pseudo-component without interaction. According to the DTG results, the reaction can be divided into different reaction stages based on the number of overlapping fitting peaks.

[0022] Figure 4 The image shows the GCMS spectra of the pyrolysis products of component A in stages.

[0023] Reference numerals in the attached figures: 1-Mixing and feeding unit; 2-Temperature-controlled reactor; 3-Carrier gas input unit; 4-Rapid condensation unit; 5-Product collection tank. Detailed Implementation

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0025] This invention proposes a chemical synthesis method based on the co-pyrolysis of organic solid waste. It utilizes the difference in phase evolution between semi-crystalline or amorphous components and highly crystalline components in organic solid waste during the pyrolysis process. By "cross-boundary induction" to break the inherent depolymerization path of highly crystalline components and by "kinetic interception" to block the thermodynamic equilibrium path, it achieves highly selective capture of high-value-added intermediates.

[0026] This invention includes the following steps: S1. Screen the organic solid waste, take the component with semi-crystalline and / or amorphous characteristics as component A, take the component with high crystallinity characteristics as component B, mix component A and component B evenly to obtain a mixture. S2. The mixture is heated to T1 in an inert atmosphere, wherein T1 > the final melting temperature of component A, the initial melting temperature of component B ≤ T1 < the characteristic depolymerization temperature of component B, and component A reacts with component B. S3. Under the condition of purging with inert carrier gas, the temperature is raised to T2, which is the target recombination temperature, i.e. the product generation temperature. Then, the generated gaseous product is rapidly cooled to obtain the product.

[0027] Step S1 involves achieving heterogeneous component compatibility and material matching. Specifically, the organic solid waste is screened to separate component A and component B, removing the remaining unusable substances. Preferably, component A and component B are physically mixed at a mass ratio of (1:9) to (9:1), meaning that in the total mass of component A and component B, the mass percentage of component A is 10% to 90%, and the mass percentage of component B is 10% to 90%.

[0028] In this invention, the semi-crystalline and / or amorphous characteristics of component A refer to the following: unlike crystalline components, it exhibits a distinct melting and crystallization peak; it also displays an endothermic / exothermic curve for amorphous components; and the DSC curve for semi-crystalline / amorphous components shows multiple weak peaks (similar to noise). Specifically, component A has a wide melting range, such as an initial melting temperature ≥60℃ (e.g., 60–180℃), and during the heating and melting process, it is accompanied by the formation of a large number of different types of pyrolysis nuclei, such as oxyanhydride nuclei and aryl nuclei. Preferably, component A includes one or more of the following: organic solid waste containing oxyanhydride and / or ester cores, organic solid waste containing benzene ring and / or benzyl cores, organic solid waste containing nitrogen free radicals, and organic solid waste containing conjugated double bond cores. Examples include waste composite packaging materials rich in aliphatic-aromatic copolyesters and amorphous polystyrene waste. Examples include multiple free radical cores that can release strong chemical affinity (containing oxygen, benzene rings, and double bonds), such as PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PC (polycarbonate), ABS (acrylonitrile-butadiene-styrene copolymer), PLA (polylactic acid), PBAT (polybutylene terephthalate), PCL (polycaprolactone), starch-based plastics, lignin, and waste rubber (such as styrene-butadiene rubber SBR).

[0029] In this invention, the high crystallinity characteristic of component B refers to the fact that component B has a single high-temperature melting point and high crystallinity. Specifically, the melting point (i.e., final melting temperature) of component B is >180℃, and there is a strong physical cross-linking network between the macromolecular chain segments of component B. For example, component B has a crystallinity of not less than 50% (≥50%), a melting enthalpy of not less than 60 J / g (≥60 J / g), a melting point of more than 180℃ (>180℃), and a melting range half-peak width of not more than 15℃ (≤15℃). Its molecular chains form regular crystalline regions through hydrogen bonds, high entanglement density, or van der Waals forces. Preferably, component B includes one or both of the following: organic solid waste containing linear aliphatic polyamides and organic solid waste of high crystallinity polyolefins, such as waste textiles and / or engineering waste rich in linear aliphatic polyamides, high-density polyethylene waste, such as PP (isotactic polypropylene, high crystallinity), PA66 (polyamide 66, nylon 66), PA12 (polydodecyl lactam, nylon 12), POM (polyoxymethylene), PTFE (polytetrafluoroethylene), UHMWPE (ultra-high molecular weight polyethylene), certain cellulose derivatives with high crystallinity, etc.

[0030] In step S2, T1 is higher than the initial melting temperature (i.e., the melting initiation temperature) of component B, causing the amorphous regions and grain boundaries of component B to begin to soften and melt. However, due to the strong physical cross-linking network (hydrogen bonds, high entanglement density) in the crystalline regions of component B, the main body of its crystalline regions remains in a state of incomplete melting or incomplete disintegration within the limited reaction time (e.g., within 5–10 min). The crystal changes of polymer materials include the glassy state (below the melting initiation temperature), the elastic state, and the viscous flow state. Further increases in temperature lead to the thermal decomposition stage. At temperature T1, component B is in the elastic and viscous flow states, and its chemical structure remains basically unchanged.

[0031] It should be noted that the characteristic depolymerization temperature (i.e., decomposition temperature, Td) of component B refers to the temperature at which the chemical bonds on the main molecular chain of the polymer break when heated, resulting in a decrease in molecular weight and the formation of monomers or small molecule products. The relationship between the melting point (final melting temperature, Tm) of component B and the characteristic depolymerization temperature Td is: Td > Tm.

[0032] In step S2, when the temperature reaches T1, which is the core release temperature of component A, component A has crossed the melting range and undergone primary chain scission, releasing a large number of active free radical cores. At the same time, component B is still in a state where the crystal region is not completely disintegrated. The active cores of component A invade the grain boundaries and amorphous regions of component B, destroying the original intermolecular forces (such as hydrogen bonds) of component B, forcing component B to undergo deep random fracture below its characteristic depolymerization temperature, releasing free small molecules, such as free ammonia and short-chain olefins, which are difficult to produce in large quantities under conventional reaction pathways, and undergo in-situ condensation and recombination with the cores of component A.

[0033] In step S2, the reaction time between component A and component B is preferably 5 to 10 minutes.

[0034] Preferably, T1 is 250–380℃.

[0035] Preferably, in step S2, the heating rate is 10–50 °C / min.

[0036] In step S3, the condensation and recombination reaction after heating is completed instantly, producing metastable high-value intermediates (i.e., target products), such as cyclic imides and alkyl aromatics. Through extremely short residence time and physical stripping of the carrier with a large flow rate, the secondary reaction pathway of the intermediate to small molecule gas or condensed carbon is cut off. Finally, the rapid cooling achieves the kinetic "freezing" and capture of the product.

[0037] Preferably, T2 is 500–750℃.

[0038] Preferably, the residence time of the generated gaseous product at the target recombination temperature is τ, where τ is 0.5–5 s, more preferably 0.5–2 s. In step S3, the inert carrier gas purging rate is related to the residence time τ, meaning that the inert carrier gas purging needs to ensure that the residence time meets the requirements. For example, in a small fixed-bed / tube furnace (50–200 mL), the purging rate can be 2–10 L / min, and in a medium-sized pyrolysis reactor (0.5–2 L), the purging rate can be 10–50 L / min, to achieve a τ range of 0.5–5 s.

[0039] Preferably, the cooling temperature is ≤0℃, and more preferably, the cooling temperature is <-44℃. Rapid cooling can be achieved through absorption by dry ice organic solvent or condensation by liquid nitrogen.

[0040] Based on the above steps, this invention overcomes thermodynamic limitations to achieve unconventional product enrichment: through "cross-boundary induction," highly crystalline components are forced to deviate from their optimal depolymerization path (e.g., to avoid generating large amounts of lactam monomers) and instead recombine with heterogeneous cores. Compared to conventional co-pyrolysis without induction, the area ratio of target metastable intermediates (such as imides and alkyl aromatics) in the liquid-phase product can be increased from less than 10% conventionally to over 60% (up to over 70%).

[0041] This invention significantly improves the yield and quality of the target product through kinetic interception: by using rapid carrier gas purging combined with rapid condensation, "kinetic interception" effectively avoids secondary cracking of high-value intermediates, reducing the yield of gaseous byproducts by 15-25%, and reducing the yield of light components (C6) in liquid oil. C12) selectivity is increased by more than 40%.

[0042] The present invention has significant economic and environmental benefits: it does not require the addition of expensive catalysts, but only utilizes the physicochemical synergy between the multiphase components of organic solid waste to achieve directional conversion, which greatly reduces operating costs; at the same time, it converts low-value solid waste into high-value-added fine chemical raw materials, realizing an efficient closed loop of carbon and nitrogen resources.

[0043] Based on the above synthesis method, the equipment used in each step of this invention are all existing devices. Figure 1 The image shows one type of reaction system, including a mixing and feeding unit, a temperature-controlled reactor, a carrier gas input unit, a rapid condensation unit, and a product collection tank. The mixing and feeding unit is connected to the temperature-controlled reactor. Component A and component B are mixed evenly in the mixing and feeding unit and then fed into the temperature-controlled reactor. The carrier gas input unit is connected to the temperature-controlled reactor and feeds inert gas into the temperature-controlled reactor. The temperature-controlled reactor, the rapid condensation unit, and the product collection tank are connected in sequence. The generated gaseous product is condensed and collected in the product collection tank.

[0044] The technical solution of the present invention will be described in detail below with specific embodiments.

[0045] Example 1 In this embodiment, component A is a semi-crystalline copolyester with both flexible aliphatic and rigid aromatic chains (melting range 60-180°C, pyrolysis produces abundant oxyanhydride cores), i.e., aliphatic-aromatic copolyester; component B is a highly crystalline polyamide (melting point about 220°C, conventional depolymerization mainly produces lactams), i.e., linear polyamide.

[0046] Component A and component B are mixed at a mass ratio of 1:1 and fed into a pyrolysis reactor. The temperature is increased at 30℃ / min to the core release temperature of component A, T1 = 300℃. At this point, component A has crossed the melting range and released a large number of oxygen-containing / benzene-ring-containing active cores. The cores of component A invade the amorphous region and grain boundaries of component B, disrupting the hydrogen bond network and forcing the amide bonds of component B to undergo deamination-type deep random breakage, releasing free amino groups and short-chain fragments, which then condense in situ with the anhydride cores of component A. Subsequently, the reactor temperature is rapidly increased to the target recombination temperature, T2 = 700℃, while nitrogen gas is introduced at a flow rate of 1 L / min to control the residence time of the gaseous products at 700℃ to be extremely short. The products are then immediately purged into a liquid nitrogen condenser (< 44℃).

[0047] GCMS spectra of the cooled products are as follows Figure 2 As shown, the peak area ratio represents the mass ratio of this type of component in the product. The main peak in the range of 18~21 min is the characteristic peak of high-value imide derivatives. The detection of the cooled product shows that the proportion of high-value imide derivatives is 70.3%.

[0048] Example 2 The difference between this embodiment and Embodiment 1 is that: component A and component B are mixed at a mass ratio of 1:4, and the target recombination temperature T2 = 550°C. The remaining steps are the same as in Embodiment 1.

[0049] Analysis of the cooled products showed that high-value imide derivatives accounted for 67%. The GC-MS spectrum of the cooled products is shown below. Figure 2 As shown.

[0050] Caprolactam is the main product of the pyrolysis of component B (PA) alone in the examples, and it is also a constituent monomer of PA. Without crosslinking, caprolactam is its core pyrolysis product. (This is in conjunction with Examples 1-2 and...) Figure 2 It can be seen that the retention times of the 18-21 min peaks in Example 1 and Example 2 are basically the same (the retention time drifts by about 0.35 min), which proves that a high-value derivative of the same type of imide was generated. At the same time, the caprolactam monomer peak disappeared and the small molecule cleavage product peaks were less in the figure, indicating that the conventional depolymerization path of component B was broken and its fragments were recombined with the core released by component A.

[0051] Comparative Example 1 This comparative model lacks dynamic interception.

[0052] Compared with Example 1, in this comparative example, the carrier gas was stopped after the temperature was rapidly raised to the target recombination temperature T2=550°C, and the gaseous products were allowed to remain naturally in the high-temperature zone for more than 15 seconds before being slowly discharged and condensed. The remaining steps were the same as in Example 1.

[0053] The results showed that the proportion of cyclic imide derivatives in the cooled product plummeted to 6.2%, while the yield of small molecule gas soared to 48 wt%, proving that recombinant intermediates could not be captured without "kinetic interception".

[0054] Comparative Example 2 This comparative model lacks cross-boundary guidance.

[0055] Component A and component B are placed in two separate reactors. Component A generates gaseous nuclei at 320°C, while component B depolymerizes at 550°C. The two materials merge in a mixing chamber at 600°C and condense after 1.2 seconds.

[0056] The products of pyrolysis of component A (PBAT) alone are complex, and there are no characteristic products in the staged pyrolysis (such as...). Figure 3 As shown); the GCMS spectrum has many small peaks (such as...). Figure 4 (as shown), and the product is not related to Examples 1 and 2, combined with Figure 2 This indicates that cross-boundary induced recombination completely altered the product structure of component A.

[0057] The results showed that the cooled products were basically the sum of individual pyrolysis products. Component B still mainly produced caprolactam (accounting for 58%), and the characteristic imide interaction products accounted for only 9.8%. This proves that the lack of "cross-boundary invasion" of component A into the crystal region of component B in the molten state cannot break the inherent depolymerization path of component B.

[0058] As can be seen from the products of Examples 1-2 and Comparative Examples 1-2, the present invention achieves its effect through specific component compatibility with "inducing" The spatiotemporal coordinated control of "interception" has subverted the product distribution of conventional pyrolysis, enabling the efficient and targeted preparation of high-value-added chemicals.

[0059] The embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A chemical synthesis method based on the co-pyrolysis of organic solid waste, characterized in that, Includes the following steps: S1. Screen the organic solid waste, take the component with semi-crystalline and / or amorphous characteristics as component A, take the component with high crystallinity characteristics as component B, mix component A and component B evenly to obtain a mixture. S2. The mixture is heated to T1 in an inert atmosphere, wherein T1 > the final melting temperature of component A, the initial melting temperature of component B ≤ T1 < the characteristic depolymerization temperature of component B, and component A reacts with component B. S3. Under the condition of purging with inert carrier gas, the temperature is rapidly increased to T2, which is the product generation temperature. Then, the generated gaseous product is rapidly cooled to obtain the product.

2. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 1, characterized in that, In step S1, the mass ratio of component A to component B is (1:9) to (9:1).

3. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 1, characterized in that, In step S2, T1 is 250–380°C.

4. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 1, characterized in that, In step S3, T2 is 500–750°C.

5. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 1, characterized in that, In step S3, the generated gaseous product has a residence time of τ at T2, where τ is 0.5 to 5 s.

6. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 1, characterized in that, In step S3, the cooling temperature is < -44℃.

7. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 1, characterized in that, The initial melting temperature of component A is ≥60℃.

8. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 7, characterized in that, Component A includes one or more of the following: organic solid waste containing oxyanhydrides and / or esters, organic solid waste containing benzene rings and / or benzyl groups, organic solid waste containing nitrogen free radicals, and organic solid waste containing conjugated double bonds.

9. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 1, characterized in that, The melting point of component B is >180℃.

10. The chemical synthesis method based on co-pyrolysis of organic solid waste according to claim 9, characterized in that, Component B includes one or both of the following: organic solid waste containing linear aliphatic polyamides and highly crystalline polyolefin organic solid waste.

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