Method for hydrodechlorination and desiliconization of waste plastic oil

Abstract

The application discloses a method for removing Cl and Si from waste plastic oil by hydrogenation, which comprises the following steps: removing Cl and Si from waste plastic oil by using a slurry bed reactor under the action of a hydrogenation catalyst and hydrogen, and finally obtaining waste plastic oil products with Cl less than 0.2 mu g / g and Si less than 1 mu g / g; the hydrogenation catalyst is a compounded catalyst formed by an oil-soluble catalyst and a powder catalyst after alkali treatment; and the deactivated catalyst after recycling is regenerated to obtain the powder catalyst after calcination, primary alkali treatment, secondary alkali treatment and grinding; thus, the problems of the influence of the removal of Si and Cl elements in the waste plastic oil on the catalytic material, device equipment and product properties and the difficulty in regeneration of the hydrogenation dechlorination and desiliconization catalyst are solved.

Description

Technical Field

[0001] This invention relates to the field of waste oil treatment technology, and specifically to a method for hydrogenating and dechlorinating waste plastic oil. Background Technology

[0002] Between 1950 and 2015, approximately 8.3 billion tons of waste plastics were generated globally, of which about 79% were landfilled or directly discharged, causing severe environmental damage. By 2019, in my country, about 32% of waste plastics were landfilled and about 31% were incinerated, causing serious pollution to both soil and air. The high-value recycling and utilization of waste plastics has become a hot topic in recent years. Waste plastic oiling technology is an important chemical recycling technique for transforming waste plastics into higher-value products. However, because waste plastics contain a certain amount of Cl and Si elements, and some of these elements are transferred into the waste plastic oil during the oiling process, it significantly affects the catalytic materials, equipment, and product properties in the waste plastic oil processing and upgrading process, such as catalyst poisoning and deactivation, and equipment corrosion. Therefore, how to effectively remove Cl and Si impurities from waste plastic oil is one of the key issues facing the industrial recycling and utilization of waste plastics.

[0003] Hydrotreating oil is an important method for deep deimpurification and quality improvement, and utilizing the hydrogenation reaction process to achieve deep dechlorination / siliconization of waste plastic oil has good application prospects. However, in the current process of hydrodechlorination and desiliconization, Cl and Si elements easily cause deactivation and blockage of the hydrogenation catalyst and are difficult to regenerate, affecting the equipment operation cycle. For example, Chinese patent document CN111171865A discloses a dechlorination method for waste plastic pyrolysis oil, which involves reacting the waste plastic pyrolysis oil with hydrogen in the presence of a hydrogenation catalyst, and then mixing the hydrogenated product oil with an adsorbent for adsorption treatment to obtain the dechlorinated oil. Chinese patent document CN114437764A discloses a desiliconization method and system for silicon-containing hydrocarbon raw materials, which involves introducing silicon-containing raw materials into a hydrogenation reactor in the presence of hydrogen and contacting them with a hydrogenation catalyst to carry out a desiliconization reaction under hydrogenation reaction conditions. The hydrogenation reactor is at least one fixed-bed hydrogenation reactor and / or at least one moving-bed hydrogenation reactor, and the silicon content of the liquid phase material in the reaction effluent is less than 1.0 μg / g. Chinese patent document CN114437763A discloses a method and system for hydrogenation pretreatment of waste plastic oil and / or waste tire oil. The method involves introducing waste plastic oil and waste tire oil into a hydrogenation reactor in the presence of hydrogen, where they contact a waste hydrogenation catalyst and a dechlorination agent. Under hydrogenation reaction conditions, desulfurization, desiliconization, and demetallization reactions are performed. The resulting reaction effluent has a silicon content of less than 1 μg / g, a chlorine content of less than 0.5 μg / g, and a metal content of less than 5 μg / g. However, this method uses a waste hydrogenation catalyst for hydrogenation and impurity removal. The waste catalyst has limited capacity to dissolve impurities such as chlorine, silicon, and metals, leading to rapid catalyst deactivation and impacting the operating cycle of the equipment.

[0004] To address the aforementioned issues, existing technologies mostly extend the operating cycle of the unit by switching to a fixed-bed reactor or using a moving-bed reactor. However, switching to a fixed-bed reactor leads to unit wear and tear, increasing operating costs; moving-bed reactors require larger amounts of catalyst and have a more complex structure; furthermore, the hydrogenation catalysts used in both fixed-bed and moving-bed reactors are prone to deactivation and are difficult to regenerate after chlorine and silicon removal, further increasing catalyst costs. Therefore, how to reduce the cost of the unit and catalyst while ensuring effective chlorine and silicon removal from waste plastic oil is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a method for the hydrodechlorination and desiliconization of waste plastic oil. A composite catalyst, formed by combining an oil-soluble catalyst and an alkali-treated powdered catalyst, is used in a slurry bed reactor for the hydrogenation reaction. This enhances the removal of Cl and Si elements while allowing the composite catalyst to be discharged from the slurry bed reactor along with the product, without affecting the operation of the equipment. Furthermore, the discharged catalyst can be recycled back into the slurry bed reactor with the waste plastic oil until it becomes deactivated. The deactivated hydrogenation catalyst is regenerated through calcination, alkali treatment, and grinding to obtain a powdered catalyst. The oil-soluble catalyst primarily increases the number of active sites, while the powdered catalyst, with its large specific surface area and pore volume, provides a carrier for Cl and Si elements, carrying them out of the reaction system. The method for the hydrodechlorination and desiliconization of waste plastic oil provided by the present invention has excellent dechlorination and desiliconization effects, reducing equipment wear and tear and costs.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for hydrogenating and dechlorinating waste plastic oil includes the following steps: a hydrogenation catalyst, waste plastic oil and hydrogen flow from bottom to top in a slurry bed reactor to carry out dechlorination and desiliconization reactions, to obtain a product with Cl<0.2μg / g and Si<1μg / g;

[0008] The hydrogenation catalyst is a composite catalyst formed by an oil-soluble catalyst and an alkali-treated powdered catalyst.

[0009] The powdered catalyst is supported on silicon dioxide.

[0010] Optionally, in the above-mentioned method for hydrodechlorination and desiliconization of waste plastic oil, the alkaline treatment process includes:

[0011] The powdered catalyst is soaked in an alkaline solution at 60-100℃ and 0.2-1.0 mol / L for 0.5-3 hours, and then washed, dried and ground to obtain the alkaline-treated powdered catalyst.

[0012] Optionally, in the alkaline treatment process of the above-mentioned method for hydrogenation dechlorination and desiliconization of waste plastic oil, the alkaline solution is selected from at least one of ammonia water, sodium hydroxide solution, potassium hydroxide solution, etc.

[0013] Optionally, in the above-mentioned method for hydrodechlorination and desiliconization of waste plastic oil, the active component of the powdered catalyst includes at least one of Co, Mo and W;

[0014] The oil-soluble catalyst can be any conventional one used in the industry, and the active component of the oil-soluble catalyst recommended in this invention is Mo.

[0015] Preferably, in the above-mentioned method for hydrogenating and dechlorinating waste plastic oil, the content of the active component in the powdered catalyst is 5wt%-30wt%, based on the mass of the powdered catalyst being 100%.

[0016] Optionally, in the above-mentioned method for hydrodechlorination and desiliconization of waste plastic oil, the specific surface area of ​​the powdered catalyst is 320-600 m². 2 / g, pore volume 0.6-1cm 3 / g.

[0017] Optionally, in the above-mentioned method for hydrotreating and desiliconizing waste plastic oil, the oil-soluble catalyst and the powdered catalyst are added at a rate of 100-2000 ppm based on the mass of the active components and the mass of the waste plastic oil as 100%, respectively; preferably, the oil-soluble catalyst is added at a rate of 300-1000 ppm and the powdered catalyst is added at a rate of 3-6 wt%.

[0018] Optionally, in the above-mentioned method for hydrodechlorination and desiliconization of waste plastic oil, the temperature of the dechlorination and desiliconization reaction is 300-420℃, the pressure is 2-10MPa, and the liquid hourly space velocity is 0.1-0.6h. -1 The hydrogen-to-oil ratio is 200-1200;

[0019] Preferably, the dechlorination and desilication reactions are carried out at a temperature of 360-400℃, a pressure of 4-8 MPa, and a liquid hourly space velocity of 0.1-0.4 h⁻¹. -1 The hydrogen-to-oil ratio is 600-1000.

[0020] Optionally, in the above-mentioned method for hydrogenating and dechlorinating waste plastic oil, when the Cl content in the product is ≥0.2 μg / g or the Si content is ≥1 μg / g, it indicates that the hydrogenation catalyst is deactivated, and a fresh hydrogenation catalyst can be replaced to continue the reaction in the slurry bed reactor. The material discharged from the slurry bed reactor is subjected to gas-liquid-solid separation, and the solid obtained is the deactivated hydrogenation catalyst. This deactivated hydrogenation catalyst is regenerated by sequentially undergoing calcination, primary alkali treatment, secondary alkali treatment, deionized water washing, drying, and grinding to obtain a regenerated powdered catalyst.

[0021] Optionally, in the above-mentioned method for hydrodechlorination and desiliconization of waste plastic oil, during the regeneration process of the deactivated powdered catalyst, the calcination temperature is 450-700℃, preferably 500-600℃, and the calcination time is 2-8h.

[0022] The primary alkali treatment process uses ammonia water as the alkali solution; the secondary alkali treatment process uses at least one of ammonia water, sodium hydroxide solution, and potassium hydroxide solution. The specific concentration of the alkali solution is not specifically limited; for example, the primary alkali treatment may involve soaking in ammonia water at 60-100℃ and 0.2-1.0 mol / L for 0.5-3 hours, and the secondary alkali treatment may involve soaking in an alkali solution at 60-100℃ and 0.2-1.0 mol / L for 0.5-3 hours.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] Beneficial effect 1: The method for hydrogenation dechlorination and desiliconization of waste plastic oil provided by the present invention adopts a slurry bed reactor. The hydrogenation catalyst can be removed or added online, without the need to extend the operating cycle by switching reactors. Moreover, the slurry bed reactor has a simpler structure and requires less catalyst than the moving bed reactor.

[0025] Beneficial Effect 2: The method for hydrotreating and desiliconizing waste plastic oil provided by this invention utilizes a composite catalyst formed by an oil-soluble catalyst and an alkali-treated powdered catalyst, which is beneficial for the generation of highly active sites and the dispersion of active metals. The powdered catalyst has a relatively large specific surface area and pore volume, providing more reaction space and silicon-containing capacity; the good dispersion effect of the oil-soluble catalyst provides more active sites, promoting dechlorination and desiliconization. Furthermore, by alkali-treating the powdered catalyst in the hydrogenation catalyst, the hydroxyl sites in the hydrogenation catalyst are effectively increased, which on the one hand improves the dispersion of active sites (active components) in the catalyst, and on the other hand improves the dechlorination and desiliconization effect.

[0026] Beneficial Effect 3: The method for hydrotreating and desiliconizing waste plastic oil provided by this invention utilizes a significantly larger amount of powdered catalyst with a large specific surface area and pore volume compared to oil-soluble catalysts. This provides a carrier for the removal of Cl and Si elements from the waste plastic oil, carrying them out of the reaction system, while the influence of Cl and Si elements on the oil-soluble catalyst is relatively small. Furthermore, the powdered catalyst carrier is silicon dioxide, which reduces the influence of silicon elements in the waste plastic oil. Later, the deactivated powdered catalyst is calcined to remove C and H elements from the silicon-containing compounds attached to it; Si remains directly in the powdered catalyst. Further primary and secondary alkali treatments replace Cl elements on the catalyst surface and modify and regenerate the pores, surface properties, and hydroxyl sites of the powdered catalyst. Finally, the catalyst is ground into powder for reuse. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a method for hydrogenating and dechlorinating waste plastic oil according to the present invention.

[0028] 1. Hydrogen; 2. Chlorine- and silicon-containing waste plastic oil; 3. Slurry bed reactor; 4. Waste plastic oil products. Detailed Implementation

[0029] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0030] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0031] Any waste plastic oil containing Cl and Si can meet the requirements for implementing the technical solution of this invention. However, for ease of comparison, the waste plastic oil with the following properties is used in the following embodiments and comparative examples.

[0032] Table 1 Properties of Waste Plastic Oil

[0033] parameter numerical values <![CDATA[Density (g / cm 3 )]]> 0.8949 <![CDATA[Viscosity (50°C) mm 2 / s]]> 9.892 Distillation range (°C) 65～706 Cl(μg / g) 2986.4 SI (μg / g) 362.7

[0034] Existing oil-soluble catalysts can all meet the requirements for implementing the technical solution of this invention. However, for ease of comparison, molybdenum isooctanoate is used in all the following examples and comparative examples.

[0035] Example 1

[0036] This embodiment provides a method for hydrogenating and dechlorinating waste plastic oil, such as... Figure 1 As shown, the specific steps are as follows:

[0037] The hydrogenation catalyst is a fresh agent, of which the oil-soluble catalyst is molybdenum isooctanoate; the active components of the powdered catalyst are Co and Mo.

[0038] Based on the mass of the active components, the total active component content in the powdered catalyst is 30 wt% (based on the mass of the powdered catalyst being 100%), of which Co content is 5 wt% and Mo content is 25 wt%. The support is silica, and the specific surface area of ​​this powdered catalyst is 600 m². 2 / g, pore volume 0.6cm 3 / g.

[0039] Among them, the powdered catalyst is used after alkali treatment. The alkali treatment conditions are as follows: the powdered catalyst is soaked in a potassium hydroxide solution with a concentration of 1.0 mol / L at 60℃ for 0.5 h, then washed with deionized water, dried at 80℃, and ground to obtain the alkali-treated powdered catalyst.

[0040] Based on the active component (metal), 300 ppm of oil-soluble catalyst, 6 wt% of alkali-treated powdered catalyst, chlorine-containing and silicon-containing waste plastic oil 2, and hydrogen gas 1 were introduced into a slurry bed reactor 3, flowing upwards. The reaction was carried out at 360°C, a pressure of 8 MPa, and a liquid hourly space velocity of 0.3 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 600, dechlorination and desilication reactions are carried out. The liquid phase obtained after gas-liquid-solid separation of the material discharged from the slurry bed reactor is the dechlorinated and desilication waste plastic oil product 4. The gas phase contains unreacted hydrogen (which can be reused after purification). The solid phase is a hydrogenation catalyst (which can be recycled back to the slurry bed reactor until the hydrogenation catalyst is deactivated).

[0041] After the above-mentioned hydrogenation catalyst is deactivated through multiple cycles (the hydrogenation catalyst is considered deactivated when Cl ≥ 0.2 μg / g or Si ≥ 1 μg / g in the dechlorinated and desiliconized waste plastic oil product), the deactivated hydrogenation catalyst (the solid obtained from gas-liquid-solid separation) is calcined at 500℃ for 8 hours, then soaked in 1.0 mol / L ammonia water at 100℃ for 3 hours, and then soaked in 0.2 mol / L sodium hydroxide solution at 60℃ for 0.5 hours. After washing with deionized water and drying, it is ball-milled at room temperature to obtain a regenerated powdered catalyst (the regenerated powdered catalyst does not require further alkali treatment before use).

[0042] Example 2

[0043] This embodiment provides a method for hydrogenating and dechlorinating waste plastic oil. The hydrogenation catalyst used is a fresh catalyst, wherein the oil-soluble catalyst is molybdenum isooctanoate; the active metals of the powdered catalyst are Co and W. Based on the mass of the active components (metals), the total active component content in the powdered catalyst is 5 wt% (based on the mass of the powdered catalyst being 100%), wherein the Co content is 0.5 wt%, the W content is 4.5 wt%, and the support is silica; the specific surface area of ​​the powdered catalyst is 320 m². 2 / g, pore volume 1.0cm 3 / g.

[0044] Among them, the powdered catalyst is used after alkali treatment. The alkali treatment conditions are as follows:

[0045] The powdered catalyst was immersed in a 0.2 mol / L sodium hydroxide solution at 100°C for 3 hours, then washed with deionized water, dried at 80°C, and ground to obtain the alkali-treated powdered catalyst.

[0046] Based on the active component (metal), 1000 ppm of oil-soluble catalyst, 3 wt% of alkali-treated powdered catalyst, chlorine-containing and silicon-containing waste plastic oil 2, and hydrogen gas 1 were introduced into a slurry bed reactor 3 and flowed upwards. The reaction was carried out at 400°C, a reaction pressure of 4 MPa, and a liquid hourly space velocity of 0.4 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 1000, dechlorination and desilication reactions were carried out. The material discharged from the slurry bed reactor was separated into gas, liquid and solid phases to obtain dechlorinated and desilication liquid waste plastic oil product 4.

[0047] After the above-mentioned hydrogenation catalyst is deactivated through multiple cycles (deactivated when Cl ≥ 0.2 μg / g or Si ≥ 1 μg / g in the dechlorinated and desiliconized waste plastic oil product), the deactivated hydrogenation catalyst (the solid obtained from gas-liquid-solid separation) is calcined at 600℃ for 2 hours, then soaked in 0.2 mol / L ammonia water at 100℃ for 0.5 hours, and then soaked in a mixed solution of 1.0 mol / L ammonia water and 0.2 mol / L potassium hydroxide solution at 60℃ in a mass ratio of 2:1 for 3 hours. After washing with deionized water and drying, it is ball-milled at room temperature to obtain a regenerated powdered catalyst (the regenerated powdered catalyst does not require further alkali treatment before use).

[0048] Example 3

[0049] This embodiment provides a method for hydrogenating and dechlorinating waste plastic oil, wherein the powdered catalyst used in the hydrogenation catalyst is the powdered catalyst obtained after regeneration in Example 1; and the oil-soluble catalyst is molybdenum isooctanoate.

[0050] Based on the active component (metal), 600 ppm of oil-soluble catalyst, 5 wt% of regenerated powdered catalyst, chlorine- and silicone-containing waste plastic oil 2, and hydrogen gas 1 are fed into a slurry bed reactor 3, flowing upwards. The reaction is carried out at 380°C, a reaction pressure of 6 MPa, and a liquid hourly space velocity of 0.2 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 800, dechlorination and desilication reactions were carried out. The material discharged from the slurry bed reactor was separated into gas, liquid and solid phases to obtain dechlorinated and desilication waste plastic oil product 4.

[0051] After the above-mentioned hydrogenation catalyst is deactivated through multiple cycles (deactivated when Cl ≥ 0.2 μg / g or Si ≥ 1 μg / g in the dechlorinated and desiliconized waste plastic oil product), the deactivated hydrogenation catalyst (the solid obtained from gas-liquid-solid separation) is calcined at 550℃ for 6 hours, then soaked in 0.5 mol / L ammonia water at 80℃ for 2 hours, and then soaked in a mixed solution of 0.2 mol / L sodium hydroxide solution and 0.5 mol / L ammonia water at a mass ratio of 1:1 at 80℃ for 2 hours. After washing with deionized water and drying, it is ball-milled at room temperature to obtain a regenerated powdered catalyst (the regenerated powdered catalyst does not require further alkali treatment before use).

[0052] Example 4

[0053] This embodiment provides a method for hydrogenating and dechlorinating waste plastic oil, wherein the powdered catalyst used in the hydrogenation catalyst is the powdered catalyst obtained after regeneration in Example 2; and the oil-soluble catalyst is molybdenum isooctanoate.

[0054] Based on the active component (metal), 400 ppm of oil-soluble catalyst and 4 wt% of regenerated powdered catalyst, along with chlorine- and silicone-containing waste plastic oil 2 and hydrogen gas 1, were introduced into a slurry bed reactor 3 and flowed upwards. The reaction was carried out at 380°C, a pressure of 8 MPa, and a liquid hourly space velocity of 0.1 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 300, dechlorination and desilication reactions were carried out. The material discharged from the slurry bed reactor was separated into gas, liquid and solid phases to obtain dechlorinated and desilication waste plastic oil product 4.

[0055] After the above-mentioned hydrogenation catalyst is deactivated through multiple cycles (deactivated when Cl ≥ 0.2 μg / g or Si ≥ 1 μg / g in the dechlorinated and desiliconized waste plastic oil product), the deactivated hydrogenation catalyst (the solid obtained from gas-liquid-solid separation) is calcined at 550℃ for 4 hours, then soaked in 1.0 mol / L ammonia water at 100℃ for 2 hours, and then soaked in a mixed solution of 1.0 mol / L potassium hydroxide solution and 0.2 mol / L ammonia water at a mass ratio of 1:2 at 60℃ for 1 hour. After washing with deionized water and drying, it is ball-milled at room temperature to obtain a regenerated powdered catalyst (the regenerated powdered catalyst does not require further alkali treatment before use).

[0056] Example 5

[0057] This embodiment provides a method for hydrogenating and dechlorinating waste plastic oil. The hydrogenation catalyst used is a fresh catalyst, wherein the oil-soluble catalyst is molybdenum isooctanoate; the active metals of the powdered catalyst are Co, Mo, and W. Based on the mass of the active components (metals), the total active component content in the powdered catalyst is 20 wt% (based on the mass of the powdered catalyst being 100%), wherein the Co content is 3%, the Mo content is 10 wt%, and the W content is 7 wt%, and the support is silica; the specific surface area of ​​the powdered catalyst is 480 m². 2 / g, pore volume 0.8cm 3 / g.

[0058] Among them, the powdered catalyst is used after alkali treatment. The alkali treatment conditions are as follows:

[0059] The powdered catalyst was soaked in an ammonia solution with a concentration of 0.6 mol / L at 80°C for 2 hours, then washed with deionized water, dried at 80°C, and ground to obtain the alkali-treated powdered catalyst.

[0060] Based on the active component (metal), 120 ppm of oil-soluble catalyst and 8 wt% of powdered catalyst, along with chlorinated and silicone-containing waste plastic oil 2 and hydrogen gas 1, were introduced into a slurry bed reactor 3 and flowed upwards. The reaction was carried out at 320°C, a pressure of 10 MPa, and a liquid hourly space velocity of 0.1 h⁻¹. -1 Under the condition of a hydrogen-to-oil ratio of 1200, dechlorination and desilication reactions were carried out. The material discharged from the slurry bed reactor was separated into gas, liquid and solid phases to obtain dechlorinated and desilication waste plastic oil product 4.

[0061] After the above-mentioned hydrogenation catalyst is deactivated through multiple cycles (deactivated when Cl ≥ 0.2 μg / g or Si ≥ 1 μg / g in the dechlorinated and desiliconized waste plastic oil product), the deactivated hydrogenation catalyst (the solid obtained from gas-liquid-solid separation) is calcined at 650℃ for 2 hours, then soaked in 0.2 mol / L ammonia water at 100℃ for 0.5 hours, and then soaked in a mixed solution of 1.0 mol / L ammonia water and 0.2 mol / L potassium hydroxide solution at 60℃ in a mass ratio of 1:2 for 3 hours. After washing with deionized water and drying, it is ball-milled at room temperature to obtain the regenerated powdered catalyst (the regenerated powdered catalyst does not require alkali treatment again before use).

[0062] Comparative Example 1

[0063] The method for hydrogenating and dechlorinating waste plastic oil provided in this comparative example is similar to that in Example 3, except that the hydrogenation catalyst used is different. The hydrogenation catalyst in this comparative example 1 is an oil-soluble catalyst (the same as the oil-soluble catalyst in Example 3).

[0064] Comparative Example 2

[0065] The method for hydrogenating and dechlorinating waste plastic oil provided in this comparative example is similar to that in Example 1, except that the hydrogenation catalyst used is different. The hydrogenation catalyst in this comparative example 1 is only a powdered catalyst (the same as the powdered catalyst in Example 1).

[0066] Comparative Example 3

[0067] The method for hydrogenating and dechlorinating waste plastic oil provided in this comparative example is similar to that in Example 1, except that the hydrogenation catalyst used is different. The powdered catalyst used in this comparative example 1 has not been treated with alkali.

[0068] The Cl and Si element contents in the dechlorinated and desiliconized waste plastic oil products obtained in the above embodiments and comparative examples are shown in the table below.

[0069] Table 1

[0070]

[0071] As shown in the table above, the present invention utilizes a mixed catalyst, formed by combining an oil-soluble catalyst and an alkali-treated powdered catalyst, to conduct a hydrogenation reaction in a slurry bed reactor, effectively improving the dechlorination and desiliconization of waste plastic oil. Furthermore, because the powdered catalyst employs a silica support with a large specific surface area and large pore volume, it possesses strong silica-containing capacity and effectively alleviates the problem of catalyst regeneration due to Si element adhesion.

[0072] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for hydrogenating and dechlorinating waste plastic oil, characterized in that, The process includes the following steps: hydrogenation catalyst, waste plastic oil and hydrogen flow from bottom to top in a slurry bed reactor to carry out dechlorination and desiliconization reactions, to obtain waste plastic oil products with Cl<0.2μg / g and Si<1μg / g; The hydrogenation catalyst is a composite catalyst formed by an oil-soluble catalyst and an alkali-treated powdered catalyst. The support for the powdered catalyst is silicon dioxide; The alkaline treatment process includes: The powdered catalyst was soaked in an alkaline solution at 60-100℃ and 0.2-1.0 mol / L for 0.5-3 h, and then washed, dried and ground to obtain the alkaline-treated powdered catalyst. The active component of the powdered catalyst includes at least one of Co, Mo, and W.

2. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 1, characterized in that, The alkaline solution is selected from at least one of ammonia, sodium hydroxide, and potassium hydroxide.

3. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 1, characterized in that, The active component of the oil-soluble catalyst is Mo.

4. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 1, characterized in that, Based on the mass of the powdered catalyst, the content of the active component in the powdered catalyst is 5wt%-30wt%.

5. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 1, characterized in that, The specific surface area of ​​the powdered catalyst is 320-600 m². 2 / g, pore volume 0.6-1cm 3 / g.

6. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 3, characterized in that, The oil-soluble catalyst and the powdered catalyst are added at a rate of 100-2000 ppm based on the mass of the active components, and the waste plastic oil is taken as 100% of the total mass. The powdered catalyst is added at a rate of 1 wt%-10 wt%.

7. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 1, characterized in that, The dechlorination and desilication reactions are carried out at a temperature of 300-420℃, a pressure of 2-10 MPa, and a liquid hourly space velocity of 0.1-0.6 h⁻¹. -1 The hydrogen-to-oil ratio is 200-1200.

8. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 1, characterized in that, When the Cl in the waste plastic oil product is ≥0.2 μg / g or Si is ≥1 μg / g, the hydrogenation catalyst is deactivated; the deactivated hydrogenation catalyst is regenerated by sequentially calcining, primary alkali treatment, secondary alkali treatment, washing, drying, and grinding.

9. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 8, characterized in that, The calcination temperature is 450-700℃, and the calcination time is 2-8 h; and / or The alkaline solution used in the primary alkaline treatment process is ammonia water; the alkaline solution used in the secondary alkaline treatment process is at least one of ammonia water, sodium hydroxide solution, and potassium hydroxide solution.

10. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 6, characterized in that, The amount of oil-soluble catalyst added is 300-1000 ppm, and the amount of powdered catalyst added is 3 wt%-6 wt%.

11. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 7, characterized in that, The dechlorination and desilication reactions are carried out at a temperature of 360-400℃, a pressure of 4-8 MPa, and a liquid hourly space velocity of 0.1-0.4 h⁻¹. -1 The hydrogen-to-oil ratio is 600-1000.

12. The method for hydrotreating and desiliconizing waste plastic oil as described in claim 9, characterized in that, The roasting temperature is 500-600℃.

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