Oil-containing solid waste and plastic co-pyrolysis method based on carbon residue in-situ catalysis

Abstract

The invention discloses an oil-containing solid waste and plastic co-pyrolysis method based on carbon residue in-situ catalysis, and belongs to the technical field of solid waste resource utilization. The method comprises the following steps: pre-treating and mixing oil-containing solid waste and waste plastic, and co-pyrolyzing to prepare primary carbon residue and pyrolysis steam; performing acid dipping or oxidation modification on the primary carbon residue to obtain modified carbon residue, performing in-situ catalytic reforming on the pyrolysis steam and the modified carbon residue under the condition that the temperature is not lower than the final pyrolysis temperature, performing fractional condensation separation on a product to obtain pyrolytic oil and hydrogen-rich gas, and performing high-valued preparation on a functional material from the secondary residue. According to the method, the problems that a catalyst needs to be additionally added and the product quality is low in the existing co-pyrolysis technology are solved. No additional catalyst is needed in the whole process, the process cost is reduced, and related secondary pollution of the catalyst is avoided; product quality improvement is effectively achieved, two kinds of solid waste are treated synchronously, and remarkable environmental protection and economic and social benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon. Background Technology

[0002] With the rapid development of the petrochemical and plastics industries, the discharge of oily solid waste (especially oily sludge) and waste plastics has surged, bringing serious environmental pressure. Oily sludge, as hazardous waste, contains a large amount of petroleum-based substances and toxic and harmful substances. Conventional disposal methods such as landfill and incineration can easily cause secondary pollution and waste resources. Polyolefin waste plastics such as polyethylene and polypropylene are difficult to degrade, resulting in significant "white pollution." Their recycling rate is low, and incineration and landfill methods pose high environmental risks. Both types of waste plastics face the dilemma of insufficient resource utilization.

[0003] Pyrolysis technology has become a research hotspot due to its ability to realize the resource utilization of solid waste and controllable secondary pollution. Existing pyrolysis technologies are mainly divided into two categories. One category is improved technologies for the separate pyrolysis of oily solid waste. For example, patent CN113881449A discloses a low-temperature pyrolysis treatment method for oily waste. Its core involves pre-treating the oily waste with a dispersant, separating the solid and liquid phases, and then pyrolyzing the solid phase at a low temperature of 200-400℃. This solves the problems of high pyrolysis temperature, easy coking, and high energy consumption associated with traditional oily solid waste pyrolysis, achieving a compliant treatment rate of less than 1wt% residual oil in the oily solid waste. However, this technology only treats oily waste separately; moreover, it requires the addition of dispersants (such as dodecylbenzenesulfonic acid solution, kerosene, white oil, etc.), increasing reagent costs. Furthermore, the recovery and treatment of the dispersant may bring additional process burdens and environmental risks.

[0004] Another type of existing technology attempts to co-pyrolyze oily solid waste and waste plastics, but it requires the addition of catalysts, which increases costs and is prone to problems such as catalyst deactivation and secondary pollution.

[0005] Therefore, there is an urgent need to develop a co-pyrolysis technology that can achieve resource utilization of residual carbon without the need for additional catalysts, improve product quality, reduce costs, and enable closed-loop utilization. Summary of the Invention

[0006] The purpose of this invention is to provide a method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon, solving the problems of existing co-pyrolysis technologies requiring external catalysts and failing to achieve resource utilization of residual carbon. The entire process requires no external catalyst, reducing process costs and avoiding secondary pollution related to catalysts; it also simultaneously treats two types of solid waste, resulting in significant environmental and socio-economic benefits.

[0007] To achieve the above objectives, this invention provides a method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon, comprising the following steps: (1) Raw material pretreatment and mixing: Dehydrate and crush the oily solid waste, crush and wash the waste plastic, and mix the pretreated oily solid waste and waste plastic at a mass ratio of (1-9):1 to obtain a mixture. (2) Co-pyrolysis: The mixture is heated to the final pyrolysis temperature and kept at the temperature for co-pyrolysis. The pyrolysis steam is removed and the primary carbon residue of the solid product is retained. (3) Residual carbon modification: Take the primary residual carbon obtained in step (2) and perform modification treatment to obtain modified residual carbon; (4) In-situ catalytic reforming: The pyrolysis steam derived in step (2) is subjected to in-situ catalytic reaction with the modified carbon residue, and the in-situ catalytic reaction temperature is ≥ the final pyrolysis temperature to obtain the reformed mixed product gas; (5) Product separation: The mixed product gas after reforming is condensed and separated, the liquid pyrolysis oil and the dehydrated hydrogen-rich gas are collected, and the solid material in the catalytic reforming zone is collected to obtain secondary residue.

[0008] Preferably, in step (1), the oily solid waste is at least one of oily sludge, tank bottom mud or oil-based drill cuttings; the waste plastic is at least one of polyethylene, polypropylene or polystyrene.

[0009] Preferably, in step (1), the moisture content of the oily solid waste after dehydration is ≤30wt%; the crushed particle size of both the oily solid waste and waste plastic is ≤10mm.

[0010] Preferably, in step (2), the mixture is pyrolyzed under an inert atmosphere or oxygen-free conditions; the inert atmosphere is a nitrogen or argon atmosphere.

[0011] Preferably, in step (2), the temperature is increased to the final pyrolysis temperature at a heating rate of 5-50℃ / min, the final pyrolysis temperature is 450-900℃, and the holding time is 30-120 minutes.

[0012] Preferably, in step (3), the modification treatment is acid immersion modification or oxidation modification.

[0013] Preferably, the acid impregnation modification is performed by impregnating the primary carbon residue with an acidic solution of 0.1-5.0 mol / L for 1-24 hours, followed by drying at 100-120℃; the acidic solution is an aqueous solution of malic acid. Oxidative modification involves subjecting primary carbon residue to a light oxidation treatment at 200-400℃ by introducing air or steam.

[0014] Preferably, in step (4), the pyrolysis steam undergoes an in-situ catalytic reaction through a fixed bed packed with modified carbon residue. The in-situ catalytic reaction temperature is 550-950℃, the height-to-diameter ratio of the fixed bed is ≥2:1, and the space velocity of the pyrolysis steam is 0.1-2.0 h⁻¹. -1 The in-situ catalytic reaction is carried out under an inert atmosphere throughout.

[0015] Preferably, in step (5), the condensation separation is a two-stage staged condensation. The first stage condensation temperature is 80°C, which separates and collects heavy pyrolysis oil and condensate. The second stage condensation temperature is 0°C, which separates and collects light pyrolysis oil and residual condensate. In the two-stage staged condensation, the heavy pyrolysis oil, light pyrolysis oil and condensate are separated by the density difference between oil and water.

[0016] The non-condensable gas after two-stage condensation is collected and then subjected to deep dehydration in a drying tower filled with molecular sieves to obtain dry hydrogen-rich gas.

[0017] Preferably, the secondary residue obtained in step (5) is activated or doped to prepare a porous adsorption material or an electrochemical energy storage material.

[0018] Preferably, the secondary residue is activated by steam at 600-800℃ or by chemical activation with KOH to prepare activated carbon adsorbent material; the doping treatment involves mixing the secondary residue with a nitrogen-containing compound in a certain mass ratio and carbonizing it at 700-900℃ under an inert atmosphere to prepare nitrogen-doped carbon electrode material.

[0019] Therefore, this invention discloses a method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon, which has the following advantages: 1. By using waste plastics as a highly efficient hydrogen donor and leveraging the natural iron and calcium metal components of oily solid waste, primary carbon residue is modified into a catalytic material, significantly improving hydrogen yield and selectivity. The degree of lightness of the pyrolysis oil is also significantly improved. No metal catalysts or molecular sieves are required throughout the process, avoiding secondary pollution caused by catalyst deactivation and metal loss.

[0020] 2. In this invention, the catalytic reaction temperature is not lower than the final pyrolysis temperature, which avoids the condensation of pyrolysis steam and promotes the cracking, reforming and deoxygenation reactions of pyrolysis steam, thus greatly reducing the complexity of the process and the operating cost.

[0021] 3. Gas-phase products are efficiently separated to obtain hydrogen-rich fuel gas and upgraded oil products. The solid residue becomes porous after a catalytic process and can be further converted into high-performance adsorbents or electrode materials. This achieves closed-loop utilization of solid waste throughout the entire process, with no solid waste discharge, resulting in significant environmental benefits and industrial economic value.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 The results show the liquid product fraction distribution of Example 1, Comparative Example 1, and Comparative Example 2. Figure 2 The results show the non-condensable gas component distribution of Example 1, Comparative Example 1, and Comparative Example 2. Detailed Implementation

[0024] This invention discloses a method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon. Oily solid waste such as oily sludge, tank bottom sludge, and oil-based drill cuttings are used in conjunction with waste plastics such as polyethylene, polypropylene, and polystyrene as raw materials. The raw materials are first homogenized and mixed through pretreatment: the oily solid waste is dehydrated to a moisture content ≤30wt% and then crushed; the waste plastics are crushed, washed to remove impurities, and both are controlled to have a particle size ≤10mm and mixed in a specific ratio. The high hydrogen-to-carbon ratio of the waste plastics provides active hydrogen during the pyrolysis process, stabilizing the heavy free radical fragments generated by the cracking of the oily solid waste, thereby inhibiting coking and increasing the yield of light products from the reaction mechanism. Simultaneously, the iron, calcium, and other metal elements inherent in the oily solid waste provide potential sources of catalytically active substances for subsequent steps.

[0025] The mixture is subjected to co-pyrolysis reaction in an inert atmosphere such as nitrogen or argon or under oxygen-free conditions. It is heated to a final pyrolysis temperature of 450-900℃ at a heating rate of 5-50℃ / min and held for 30-120 minutes. This allows the organic hydrocarbons in the material to be fully decomposed into pyrolysis vapor and continuously discharged, while the inorganic metal components and carbon matrix in the oily solid waste remain in solid form, forming primary residual carbon rich in carbon matrix and natural metal components.

[0026] The primary carbon residue is modified by acid impregnation or oxidation, and no additional catalyst is required throughout the process.

[0027] Acid impregnation modification involves impregnating primary carbon residues with a 0.1-5.0 mol / L aqueous solution of citric acid, malic acid, or phosphoric acid for 1-24 hours, followed by drying at 100-120℃, introducing acidic active sites onto the carbon residue surface. Oxidation modification involves mildly oxidizing the primary carbon residues at 200-400℃ by introducing air or steam, converting the natural metal components in the carbon residues into highly dispersed catalytically active structures. Both modification methods can transform primary carbon residues into modified carbon residues with catalytic cracking capabilities.

[0028] The pyrolysis steam generated from co-pyrolysis is introduced into a fixed bed packed with modified carbon residue for in-situ catalytic reforming. To avoid the condensation of pyrolysis steam affecting the reaction efficiency, the in-situ catalytic reaction temperature is set to be ≥ the final pyrolysis temperature and controlled within 550-950℃. Simultaneously, the height-to-diameter ratio of the fixed bed is ≥2:1, and the pyrolysis steam space velocity is 0.1-2.0 h⁻¹. -1 The entire process maintains an inert atmosphere to ensure full contact between the pyrolysis steam and the modified carbon residue. During this process, the pyrolysis steam undergoes catalytic cracking, reforming, and deoxygenation reactions, in which the heavy hydrocarbon components are converted into light aromatic hydrocarbons, chain hydrocarbons, and other high-quality oil phase components. At the same time, the dehydrogenation reaction is significantly promoted, resulting in a substantial increase in the hydrogen content of the product gas.

[0029] The reformed mixed product gas is efficiently separated by two-stage condensation. The first stage of condensation at 80℃ separates heavy pyrolysis oil, and the second stage of condensation at 0℃ separates light pyrolysis oil. The non-condensable gas after condensation is dried and dehydrated by molecular sieve to obtain high-purity hydrogen-rich gas, thus achieving efficient separation and collection of liquid pyrolysis oil and gaseous hydrogen-rich fuel. The solid material after the catalytic reforming reaction is collected as secondary residue. Because it has undergone a high-temperature process and has a specific pore structure, it can be further activated to prepare adsorbent materials or electrode materials with practical value.

[0030] The following embodiments further describe the present invention's method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon.

[0031] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0032] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0033] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art.

[0034] Example 1 Oily sludge from an oilfield, with an initial oil content of 18.5 wt%, was dehydrated by centrifugation to a moisture content of 25 wt%. The sludge was dried to constant weight at 105℃, then crushed and sieved to obtain particles with a diameter ≤5 mm. Waste polyethylene plastic was also taken, washed, dried, and crushed to a particle size ≤5 mm. The treated oily sludge and waste PE were weighed at a dry weight ratio of 1:1 and mechanically mixed thoroughly to obtain a mixture.

[0035] Approximately 100g of the mixture was placed in the corundum boat of a horizontal tubular pyrolysis furnace. High-purity nitrogen was introduced as both a protective gas and a carrier gas, with a flow rate set to 200 mL / min, and purged for 30 minutes to remove air. The reaction zone was then heated to 650℃ (denoted as the final pyrolysis temperature T1) at a heating rate of 10℃ / min and held at this temperature for 60 minutes to carry out the co-pyrolysis reaction. The pyrolysis vapors generated during the reaction were carried out with the nitrogen and discharged through a heated, insulated pipeline. After the reaction was completed, the furnace was cooled to room temperature, and the solids in the reactor were collected, recorded as primary char, weighing 45.2g.

[0036] Take 20g of the above-mentioned primary carbon residue and immerse it in 200mL of a 1.0 mol / L malic acid aqueous solution. Let it stand at room temperature for 12 hours. After filtration and separation, place the solid in an oven at 105℃ and dry it to constant weight to obtain the modified carbon residue.

[0037] The pyrolysis steam from the co-pyrolysis was fed into a separate fixed-bed catalytic reactor pre-loaded with 20g of the aforementioned modified carbon residue. The reactor was a quartz tube type, with a catalyst bed height-to-diameter ratio (height-to-diameter ratio) of 4:1. The temperature of the catalytic reaction zone was set at 750℃ (this temperature is denoted as catalytic temperature T2, T2>T1). By adjusting the carrier gas flow rate and reactor volume, the space velocity of the pyrolysis steam in the catalyst bed was controlled to be approximately 0.8 h⁻¹. -1 The product gas from catalytic reforming flows out.

[0038] The product gas undergoes two-stage condensation: the first stage, controlled at 80°C, is used to condense and recover heavy tar and water; the second stage, an ice-water bath (0°C), is used to condense and recover light oil. In both stages, the heavy pyrolysis oil, light pyrolysis oil, and condensate are separated by the density difference between oil and water. The non-condensable gas after both stages is then subjected to deep dehydration through a drying tube equipped with a 3A molecular sieve. This yields a light pyrolysis oil fraction and hydrogen.

[0039] Example 2 Take oil-based drill cuttings, dehydrate, dry, and crush them to a particle size ≤ 8 mm. Take waste polypropylene (PP) plastic, wash, dry, and crush it to a particle size ≤ 8 mm. Mix the two at a dry basis mass ratio of 2:1.

[0040] The co-pyrolysis process was carried out under an argon atmosphere, with the temperature increased to 700℃ (T1) at a rate of 20℃ / min and held for 40 minutes. The residual carbon was collected once.

[0041] The primary char residue was placed in a tube furnace with air flowing through it (50 mL / min), and heated to 300℃ at a rate of 5℃ / min. It was then held at this temperature for 60 minutes to carry out oxidative modification, resulting in modified char residue.

[0042] The catalytic reforming conditions are: T2 = 800℃, fixed bed height-to-diameter ratio 3:1, and space velocity approximately 1 h⁻¹. -1 Product analysis showed that light pyrolysis oil accounted for 68%, and the volume fraction of H2 in the hydrogen-rich gas was 28%.

[0043] Example 3 Take refinery tank bottom sludge, dehydrate it to a moisture content of 28wt%, then dry and crush it to a particle size ≤10mm. Take waste polystyrene (PS) plastic, crush and wash it to a particle size ≤10mm. Mix the two at a dry basis mass ratio of 1:2.

[0044] Co-pyrolysis conditions: nitrogen atmosphere, heating to 550℃ (T1) at 15℃ / min, and holding for 90 minutes.

[0045] The modification treatment adopts a composite method: first, the primary carbon residue is soaked in 0.5 mol / L malic acid solution for 8 hours and dried at 110℃; then it is placed in an atmosphere with water vapor and oxidized at 250℃ for 30 minutes to obtain modified carbon residue.

[0046] Catalytic reforming conditions: T2 = 650℃, fixed bed height-to-diameter ratio 5:1, space velocity approximately 0.5 h⁻¹ -1 .

[0047] Product analysis showed that light pyrolysis oil accounted for 70%, and the volume fraction of H2 in the hydrogen-rich gas was 27%.

[0048] Example 4 Oily sludge and tank bottom sludge were mixed at a mass ratio of 1:1 to form oily solid waste, which was then dehydrated and crushed to a particle size ≤6mm. Waste PE and PP were mixed at a mass ratio of 1:1 to form mixed plastic, which was then crushed to a particle size ≤6mm. Oily solid waste and mixed plastic were then mixed at a dry basis mass ratio of 3:1.

[0049] Co-pyrolysis conditions: nitrogen atmosphere, heating at 25℃ / min to 750℃ (T1), and holding at that temperature for 30 minutes.

[0050] Modification treatment: The primary carbon residue was impregnated with 2.0 mol / L malic acid solution for 6 hours and dried at 100℃ to obtain modified carbon residue.

[0051] Catalytic reforming conditions: T2 = 850℃, fixed bed height-to-diameter ratio 4:1, space velocity approximately 1.2 h⁻¹. -1 .

[0052] Product analysis showed that light pyrolysis oil accounted for 75%, and the volume fraction of H2 in the hydrogen-rich gas was 32%.

[0053] In this embodiment, the secondary residue was mixed with melamine at a mass ratio of 1:2, and carbonized at 900°C for 2 hours under argon protection by heating at 5°C / min to obtain nitrogen-doped carbon material.

[0054] Example 5 Oil-based drill cuttings and oily sludge are mixed at a mass ratio of 1:1, dehydrated, and crushed to a particle size ≤7mm. They are then mixed with waste PE at a dry basis mass ratio of 1:3 (mixed solid waste:PE).

[0055] Co-pyrolysis conditions: Argon atmosphere, heating to 600℃ (T1) at 8℃ / min, and holding for 80 minutes.

[0056] Modification treatment: The primary carbon residue was oxidized at 450°C for 45 minutes in an atmosphere with steam (flow rate 100 mL / min) to obtain modified carbon residue.

[0057] Catalytic reforming conditions: T2 = 700℃, fixed bed height-to-diameter ratio 3:1, space velocity approximately 1.6 h⁻¹ -1 .

[0058] Product analysis showed that light pyrolysis oil accounted for 69%, and the volume fraction of H2 in the hydrogen-rich gas was 29%.

[0059] The secondary residue in this embodiment can be used as an adsorbent material after being activated with steam (750°C, 1.5 hours).

[0060] Comparative Example 1 Using the oily sludge from Example 1 as raw material, without adding plastic, pyrolysis was carried out separately under the same pyrolysis conditions as in Example 1 (N2, 650°C, 60 min). The pyrolysis vapors were directly condensed and separated without catalysis.

[0061] Comparative Example 2 The same raw materials and co-pyrolysis conditions as in Example 1 were used. However, after co-pyrolysis, the pyrolysis vapors were bypassed by the catalytic reaction and directly condensed and separated.

[0062] Simulated distillation (GC) analysis was performed on the liquid products collected in Example 1 and Comparative Examples 1-2 to calculate the mass fraction of light pyrolysis oil components with boiling points below 250°C in the total oil product. The liquid product fraction distribution results are as follows: Figure 1As shown, the proportion of light oil (<250℃) in Example 1 reached 72.0%, which was significantly higher than 58.0% in Comparative Example 2 and 45.0% in Comparative Example 1. The proportions of heavy oil fraction (18.0%) at 250-350℃ and residue / wax oil fraction (10.0%) at >350℃ were the lowest among the three. This result verifies the significant improvement effect of in-situ catalytic reforming on light oil products and also shows that the catalytic process can efficiently crack heavy hydrocarbons into light components. Among them, the gasoline fraction with a temperature <180℃ accounted for 48.2%, which was 1.48 times and 2.68 times that of Comparative Example 2 and Comparative Example 1, respectively, indicating that the catalysis had a significant promoting effect on the formation of low-boiling-point light oils; the diesel fraction with a temperature of 180-250℃ accounted for 23.8%, which was slightly lower than that of Comparative Example 2 (25.5%) and Comparative Example 1 (27.0%), but combined with the significant increase in the gasoline fraction, the overall proportion of light oils remained the highest; the heavy oil fraction with a temperature of 250-350℃ accounted for significantly less than that of the two comparative examples, confirming that the catalysis can crack heavy long-chain hydrocarbons into light components; the residual oil / wax oil fraction with a temperature >350℃ accounted for only half of that of the comparative examples, which significantly reduced the proportion of high-boiling-point and difficult-to-process residual oils and improved the overall utilization rate of liquid products.

[0063] The composition of non-condensable gases after dehydration in Examples 1 and Comparative Examples 1-2 was analyzed by online gas chromatography (GC), and the results are as follows: Figure 2 As shown, the proportion of each gas component in the non-condensable gas of Example 1 is the highest among the three, followed by Comparative Example 2, and the lowest in Comparative Example 1. Specifically, hydrogen accounts for 30% in Example 1, far higher than the two comparative examples, catalyzing and promoting the deep dehydrogenation and cracking of hydrocarbons in the feedstock to generate more hydrogen-rich gas; carbon monoxide accounts for 18.5%, providing a high-quality syngas foundation for the subsequent synthesis of high-value-added chemicals. Specifically, Comparative Example 1 uses single feedstock pyrolysis without co-pyrolysis and catalysis, resulting in the weakest reaction degree, the highest proportion of low-carbon hydrocarbons (methane, C2-C4 light hydrocarbons) and carbon dioxide, and the least amount of high-value products generated, achieving only basic cracking; Comparative Example 2 enhances cracking through co-pyrolysis of mixed feedstocks, but without catalysis, resulting in a moderate reaction degree, with the proportion of each component between the two, and limited conversion efficiency; while Example 1 combines co-pyrolysis and catalysis, resulting in the strongest reaction degree, consuming low-carbon hydrocarbons and CO2, and deeply converting them into high-value products such as hydrogen, carbon monoxide, and light aromatics, while reducing the residue of heavy products. Overall, catalytic processes are key to improving conversion efficiency and product value. Compared to single pyrolysis or catalytic co-pyrolysis, the combined process of co-pyrolysis and catalysis can achieve more efficient conversion of raw materials and high-value utilization of products.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for co-pyrolyzing oily solid waste and plastics based on in-situ catalysis of residual carbon, characterized in that, Includes the following steps: (1) Raw material pretreatment and mixing: Dehydrate and crush the oily solid waste, crush and wash the waste plastic, and mix the pretreated oily solid waste and waste plastic at a mass ratio of (1-9):1 to obtain a mixture. (2) Co-pyrolysis: The mixture is heated to the final pyrolysis temperature and kept at the temperature for co-pyrolysis. The pyrolysis steam is removed and the primary carbon residue of the solid product is retained. (3) Residual carbon modification: Take the primary residual carbon obtained in step (2) and perform modification treatment to obtain modified residual carbon; (4) In-situ catalytic reforming: The pyrolysis steam derived in step (2) is subjected to in-situ catalytic reaction with the modified carbon residue, and the in-situ catalytic reaction temperature is ≥ the final pyrolysis temperature to obtain the reformed mixed product gas; (5) Product separation: The mixed product gas after reforming is condensed and separated, the liquid pyrolysis oil and the dehydrated hydrogen-rich gas are collected, and the solid material in the catalytic reforming zone is collected to obtain secondary residue.

2. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon, as described in claim 1, is characterized in that... In step (1), the oily solid waste is at least one of oily sludge, tank bottom mud or oil-based drill cuttings; the waste plastic is at least one of polyethylene, polypropylene or polystyrene.

3. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon, as described in claim 1, is characterized in that... In step (1), the moisture content of the dehydrated oily solid waste is ≤30wt%; the crushed particle size of both the oily solid waste and waste plastic is ≤10mm.

4. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon as described in claim 1, characterized in that, In step (2), the mixture is pyrolyzed under an inert atmosphere or oxygen-free conditions; the inert atmosphere is a nitrogen or argon atmosphere.

5. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon according to claim 1, characterized in that, In step (2), the temperature is increased to the final pyrolysis temperature at a heating rate of 5-50℃ / min. The final pyrolysis temperature is 450-900℃, and the holding time is 30-120 minutes.

6. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon according to claim 1, characterized in that, In step (3), the modification treatment is either acid immersion modification or oxidation modification.

7. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon according to claim 6, characterized in that, Acid impregnation modification is performed by impregnating the primary carbon residue with an acidic solution of 0.1-5.0 mol / L for 1-24 hours, followed by drying at 100-120℃; the acidic solution is an aqueous solution of malic acid. Oxidative modification involves subjecting primary carbon residue to a light oxidation treatment at 200-400℃ by introducing air or steam.

8. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon according to claim 1, characterized in that, In step (4), the pyrolysis steam undergoes an in-situ catalytic reaction through a fixed bed packed with modified carbon residue. The in-situ catalytic reaction temperature is 550-950℃, the height-to-diameter ratio of the fixed bed is ≥2:1, and the space velocity of the pyrolysis steam is 0.1-2.0 h⁻¹. -1 The in-situ catalytic reaction is carried out under an inert atmosphere throughout.

9. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon according to claim 1, characterized in that, In step (5), the condensation separation is a two-stage stage condensation. The first stage condensation temperature is 80℃, which separates and collects heavy pyrolysis oil and condensate; the second stage condensation temperature is 0℃, which separates and collects light pyrolysis oil and residual condensate. The non-condensable gas after two-stage condensation is collected and then subjected to deep dehydration in a drying tower filled with molecular sieves to obtain dry hydrogen-rich gas.

10. The method for co-pyrolysis of oily solid waste and plastics based on in-situ catalysis of residual carbon according to claim 1, characterized in that, The secondary residue obtained in step (5) is activated or doped to prepare porous adsorption materials or electrochemical energy storage materials.

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