Dechlorination method of chlorine-containing biological oil

Abstract

The invention relates to the field of biological oil and fat treatment, and discloses a dechlorination method of chlorine-containing biological oil and fat. The method comprises the following steps: (1) carrying out dechlorination and deoxidation reaction on chlorine-containing biological oil and hydrogen under the action of a hydrodeoxygenation catalyst, and then carrying out gas-liquid separation to obtain a gas-phase material flow W; (2) carrying out adsorption dechlorination on the gas-phase material flow W under the action of a gas-phase dechlorinating agent; the gas-phase dechlorinating agent comprises aluminum oxide and an active metal component; the active metal component is selected from at least one of alkali metal and alkaline earth metal; on the basis of the total weight of the gas-phase dechlorinating agent, the content of the active metal component in terms of oxide is 20-35 wt%; according to TGA characterization, the weight loss ratio of the gas-phase dechlorinating agent in the temperature range of 200-500 DEG C is 10-25%. According to the method, chlorine in the biological oil and fat can be efficiently removed, and the problem that chlorine ions corrode a device in the biological oil and fat processing process is effectively solved; meanwhile, the gas-phase dechlorinating agent has good structural stability, and the running period of the device is prolonged.

Description

Technical Field

[0001] This invention relates to the field of bio-oil processing, and more specifically to a method for dechlorinating chlorinated bio-oils. Background Technology

[0002] Bio-oils, as an important biomass feedstock, have significant applications in the field of renewable energy. Biodiesel can be directly produced from bio-oils through a hydrorefining process, a green and low-carbon production method that represents a major pathway for the high-value conversion of bio-oils. However, bio-oils have high chlorine and oxygen content, which easily generates hydrogen chloride and water during hydrorefining. Under liquid phase conditions, especially at the water dew point, hydrogen chloride and water can form highly concentrated hydrochloric acid, causing severe corrosion to reactors, heat exchangers, and related pipelines. It can also form ammonium chloride salts that clog equipment and pipelines, posing serious safety hazards to the safe and stable operation of the plant. Therefore, the removal of chlorine from bio-oils has become a key technical challenge.

[0003] CN104560413B discloses a method for hydrodechlorination treatment of waste cooking oil. It mainly uses a dechlorination adsorbent in a post-dechlorination reactor to adsorb hydrogen chloride generated during the refining process. However, the commissioning of the high-pressure dechlorination reactor results in additional equipment investment. At the same time, some of the hydrogen chloride generated during the refining process dissolves in the liquid oil at high temperature, resulting in a low chlorine penetration capacity of the dechlorination adsorbent. In order to avoid corrosion of the device by the hydrogen chloride generated during the reaction, a large amount of dechlorination adsorbent needs to be loaded to fully adsorb the hydrogen chloride.

[0004] CN117004433A discloses a method for dechlorinating waste plastic oil and / or waste tire oil. The method involves the waste plastic oil and / or waste tire oil entering a hydrogenation reactor and reacting with a hydrogenation catalyst. The resulting effluent enters a high-pressure stripping tower, and the gaseous material at the top of the high-pressure stripping tower enters a dechlorination reactor for adsorption and dechlorination. This method significantly improves the chlorine penetration capacity of the dechlorinating agent and reduces the processing cost of high-chlorine raw materials. However, in the dechlorination process of bio-oils, the reaction conditions of the gas-phase dechlorination reactor are high temperature, high pressure, and high water vapor concentration. Although traditional gas-phase dechlorinating agents have a high chlorine capacity (compared to a gas-liquid two-phase environment), their mechanical strength is low under such conditions. The catalyst strength decreases significantly or even pulverizes after one month of operation, resulting in poor dechlorination effect and short operating time. Therefore, improving the water vapor resistance of the gas-phase dechlorinating agent and maintaining its structural stability have become key issues in the dechlorination process of chlorinated oils. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor chlorine removal efficiency and short lifespan of dechlorinating agents in existing methods, which lead to equipment corrosion and short operating cycles. This invention provides a dechlorination method for chlorinated bio-oils. This method can efficiently remove chlorine from bio-oils, effectively solving the problem of chloride ion corrosion of the equipment during bio-oil processing. Simultaneously, the gas-phase dechlorinating agent used has good structural stability, effectively extending the operating cycle of the equipment.

[0006] To achieve the above objectives, the present invention provides a method for dechlorinating chlorinated biological oils, the method comprising the following steps:

[0007] (1) Chlorinated bio-oil and hydrogen are subjected to dechlorination and deoxygenation reaction under the action of hydrodeoxygenation catalyst, and then gas-liquid separation is performed to obtain gaseous stream W;

[0008] (2) The gaseous stream W is subjected to adsorption and dechlorination under the action of a gaseous dechlorination agent;

[0009] The gas-phase dechlorination agent comprises alumina and an active metal component; the active metal component is selected from at least one of alkali metals and alkaline earth metals; based on the total weight of the gas-phase dechlorination agent, the content of the active metal component, calculated as oxides, is 20-35% by weight.

[0010] According to TGA characterization, the weight loss rate of the gas-phase dechlorination agent is 10-25% in the temperature range of 200℃-500℃.

[0011] The beneficial effects of the present invention through the above technical solution include:

[0012] The dechlorination method provided by this invention involves adsorbing and dechlorinating a gaseous stream W under the action of a specific gaseous dechlorinating agent. This efficiently removes hydrogen chloride generated during the hydrogenation reaction of oils and effectively solves the corrosion problem of the equipment caused by chloride ions during the processing of bio-oils. Furthermore, the gaseous dechlorinating agent used has good structural stability, effectively extending the operating cycle of the equipment. Moreover, the dechlorination method provided by this invention is simple to operate, operates under mild conditions, and is low in cost. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] This invention provides a method for dechlorinating chlorinated bio-oils, the method comprising the following steps:

[0015] (1) Chlorinated bio-oil and hydrogen are subjected to dechlorination and deoxygenation reaction under the action of hydrodeoxygenation catalyst, and then gas-liquid separation is performed to obtain gaseous stream W;

[0016] (2) The gaseous stream W is subjected to adsorption and dechlorination under the action of a gaseous dechlorination agent;

[0017] The gas-phase dechlorination agent comprises alumina and an active metal component; the active metal component is selected from at least one of alkali metals and alkaline earth metals; based on the total weight of the gas-phase dechlorination agent, the content of the active metal component, calculated as oxides, is 20-35% by weight.

[0018] According to TGA characterization, the weight loss rate of the gas-phase dechlorination agent is 10-25% in the temperature range of 200℃-500℃.

[0019] In existing technologies, chlorinated bio-oils first undergo hydrodechlorination and hydrodeoxygenation reactions, and then pass through a dechlorination reactor for adsorption dechlorination. The problem with this method is that in a gas-liquid two-phase environment, the chlorine capacity of the dechlorinating agent in the dechlorination reactor is low, making it difficult for hydrogen chloride in the liquid phase to be adsorbed by the dechlorinating agent. In subsequent technologies, a high-pressure stripping tower is first used to separate the gas-liquid two-phase streams, and hydrogen chloride is dispersed in the gas phase through stripping. Then, it passes through a dechlorination reactor for adsorption dechlorination to increase the chlorine capacity of the dechlorinating agent. However, the gas phase dechlorination reactor is a reaction system of high temperature, high pressure, and high concentration of water vapor. Although the chlorine capacity of the gas phase dechlorinating agent is increased (compared to the gas-liquid two-phase environment), the mechanical strength and stability are low under such harsh conditions. The strength of the catalyst drops significantly or even shatters after one month of operation, resulting in poor dechlorination effect and short operating time for the oil. The method provided by the present invention effectively overcomes the above defects. First, the dechlorination and deoxygenation reaction products in step (1) are separated into gas and liquid phases. Then, a specific gas phase dechlorination agent is used to efficiently remove hydrogen chloride generated by the hydrogenation reaction of oil and fat, effectively solving the problem of chloride ion corrosion of the device during the processing of bio-oil and fat. At the same time, the gas phase dechlorination agent used has good structural stability, effectively solving the problem of short operation cycle of the dechlorination reactor.

[0020] According to the present invention, TGA characterization shows that the weight loss rate of the gas-phase dechlorinating agent in the temperature range of 200℃-500℃ is 10-25%, specifically 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, and any two of these values, preferably 10-20%. This preferred embodiment indicates that the hydroxyl content on the alumina surface within a suitable range is beneficial for stabilizing the alumina framework structure, preventing hydration reactions that could lead to structural reconstruction in the presence of water vapor during the dechlorination reaction; simultaneously, it enhances the interaction between the active metal components and alumina, reduces the loss of active metal components, and ensures that the gas-phase dechlorinating agent maintains good structural stability during the adsorption dechlorination reaction.

[0021] The thermogravimetric analysis (TGA) method described in this invention specifically includes: heating a certain mass of gas-phase dechlorinating agent from room temperature to 800℃ at a rate of 10℃ / min, and obtaining a thermogravimetric curve with temperature on the horizontal axis and mass retention rate on the vertical axis. The weight loss rate of the gas-phase dechlorinating agent within the temperature range of 200℃-500℃ is the mass retention rate at 200℃ minus the mass retention rate at 500℃.

[0022] According to the present invention, based on the total weight of the gas-phase dechlorinating agent, the content of the active metal component, calculated as oxides, is 20-35% by weight, for example, it can be 20% by weight, 21% by weight, 22% by weight, 23% by weight, 24% by weight, 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, and any two of these values ​​forming a range, more preferably 20-30% by weight. The inventors of the present invention have found that, in this preferred case, it is advantageous to improve the chlorine adsorption activity of the gas-phase dechlorinating agent.

[0023] The content of active metal components in the gas-phase dechlorination agent of the present invention was determined by X-ray fluorescence spectroscopy (XRF).

[0024] According to the present invention, preferably, the alkali metal is selected from at least one of lithium, sodium, potassium, rubidium, and cesium, more preferably sodium and / or potassium, and even more preferably sodium. This preferred embodiment results in the gas-phase dechlorination agent exhibiting higher structural stability.

[0025] According to the present invention, preferably, the alkaline earth metal is selected from at least one of magnesium, calcium, strontium, and barium, more preferably magnesium and / or calcium, and even more preferably magnesium. This preferred embodiment results in the gas-phase dechlorination agent exhibiting higher structural stability.

[0026] The gas-phase dechlorination agent of this invention has a high chlorine penetration capacity and exhibits good chlorine adsorption activity. Preferably, the chlorine penetration capacity of the gas-phase dechlorination agent is not less than 20%, and more preferably 20-30%.

[0027] The method for testing the breakthrough chlorine capacity of the gas-phase dechlorinating agent described in this invention includes: loading a certain mass of dechlorinating agent (m1) into a fixed-bed reactor; heating the reactor to 300°C at a heating rate of 5°C / min; then introducing a feed gas (nitrogen gas containing 20,000 ppm hydrogen chloride); maintaining atmospheric pressure; and setting the volume hourly space velocity (VHSV) of the feed gas to 4000 h⁻¹. -1 The experiment ends when the hydrogen chloride detector shows an outlet hydrogen chloride concentration greater than 1 ppm. The dechlorinating agent after the reaction is removed and weighed, with the mass recorded as m2. The chlorine content of the dechlorinating agent after the reaction is analyzed using X-ray fluorescence spectroscopy and recorded as w. Therefore, the chlorine capacity of the gas-phase dechlorinating agent = m2 * w / m1 * 100%.

[0028] Preferably, the specific surface area of ​​the gas-phase dechlorination agent is 150-230 cm². 2 / g, pore volume 0.5-0.7cm³ 3 / g.

[0029] The specific surface area and pore volume of the gas-phase dechlorination agent of this invention were measured by BET physical adsorption-desorption analysis.

[0030] The gas-phase dechlorination agent of this invention has high mechanical strength, which is beneficial for extending the life of the gas-phase dechlorination catalyst. Preferably, the crushing strength of the gas-phase dechlorination agent is 15-35 N / mm, more preferably 20-30 N / mm.

[0031] The crushing strength of the gas-phase dechlorination agent described in this invention is determined using a crushing strength analyzer. The determination method is as follows: The gas-phase dechlorination agent is dried at 120°C for 2 hours, then cooled to 25°C in a desiccator. Twenty samples of specific lengths are taken out for testing. The relevant measurement parameters of the crushing strength analyzer are set, a sample is placed on the sample stage, the measurement button is pressed, and the force bar is slowly lowered, increasing the pressure until the sample breaks. The pressure data is recorded and then divided by the sample length to obtain the crushing strength data. The maximum and minimum values ​​of the 20 measured catalyst crushing strength data are discarded, and the average value of the remaining data is taken as the crushing strength of the tested gas-phase dechlorination agent sample.

[0032] According to the present invention, preferably, the gas-phase dechlorination agent does not have a spinel structure. In this preferred embodiment, it is beneficial for the catalyst to fully adsorb the hydrogen chloride generated in the dechlorination reaction, further enhancing the chlorine adsorption activity of the gas-phase dechlorination agent.

[0033] It should be noted that when the gas-phase dechlorinating agent has a spinel structure, it will be detrimental to the adsorption of hydrogen chloride by the gas-phase dechlorinating agent, thus affecting the chlorine adsorption activity of the gas-phase dechlorinating agent.

[0034] This invention does not impose any particular limitation on the preparation method of the gas-phase dechlorination agent, as long as a gas-phase dechlorination agent with the above-mentioned composition and characteristic parameters can be obtained. To improve the performance of the gas-phase dechlorination agent and to better illustrate its preparation, this invention also provides a method for preparing the gas-phase dechlorination agent.

[0035] According to the present invention, preferably, the preparation method of the gas-phase dechlorination agent includes the following steps:

[0036] S1. The alumina precursor and the active metal component precursor are mixed and shaped, and then dried to obtain modified alumina.

[0037] S2. The modified alumina obtained in step S1 is calcined under steam conditions.

[0038] According to the present invention, preferably, the mass ratio of the alumina precursor to the active metal component precursor is 1-8:1, specifically 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, and any two of these values ​​forming a range, preferably 2-5:1, wherein the active metal component precursor is calculated as an active metal component oxide.

[0039] The present invention allows for a wide range of selections for the active metal component precursor, which can be conventional choices in the art, as long as it contains an active metal component. Preferably, the active metal component precursor is an oxide and / or acid salt of the active metal component.

[0040] Preferably, the acid salt of the active metal component is selected from at least one of the carbonate, nitrate and phosphate of the active metal component, preferably a carbonate of the active metal component, and more preferably a basic carbonate of the active metal component.

[0041] The present invention allows for a wide range of selections of the alumina precursor, which can be conventional choices in the field. Preferably, the alumina precursor is selected from at least one of boehmite, boehmite, alumina sol, amorphous hydrated alumina, alumina trihydrate, and boehmite monohydrate.

[0042] In the mixing process described in step S1, water may or may not be added. Generally, from the perspective of improving the uniformity of mixing, it is preferable to add water during the mixing process. The present invention does not impose a particular limitation on the amount of water used, as long as it ensures smooth subsequent molding. Preferably, the weight ratio of water to the active metal component precursor is 3-15:1.

[0043] In the mixing process described in step S1, a glue solvent and an extrusion aid may be added, or they may not be added.

[0044] This invention does not impose any particular limitations on the type and amount of the adhesive solvent and extrusion aid; they can be conventionally selected in the art to ensure successful molding. In exemplary embodiments of this invention, nitric acid is used as the adhesive solvent, and guar gum powder is used as the extrusion aid.

[0045] The present invention does not particularly limit the molding method described in step S1. Commonly used molding methods in the art can be used, such as at least one of extrusion molding, spray molding, roll forming and sheet forming. The present invention preferably uses extrusion molding.

[0046] The present invention does not impose any particular restrictions on the shape of the molded article obtained in step S1. It can be one or more of the following: spherical, honeycomb, bird's nest, sheet, and strip (such as clover, saucer, cylinder and Raschig ring).

[0047] The drying process described in step S1 can be carried out using methods conventional in the art.

[0048] The drying process in step S1 can be either oven drying or vacuum drying. Preferably, the drying conditions in step S1 include: a temperature of 60-280°C, more preferably 80-250°C, and more preferably 110-200°C; and a time of 1-48 hours, more preferably 2-24 hours, and more preferably 2-12 hours.

[0049] According to the present invention, preferably, the calcination conditions in step S2 include: a temperature of 300-600°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, or any two of these values, preferably 350-600°C; and a time of 1-10 hours, preferably 2-8 hours. This preferred embodiment is advantageous for obtaining a catalyst without a spinel structure.

[0050] According to the present invention, preferably, the steam flow rate relative to 1 kg of modified alumina is 0.01-0.3 L / h, for example, it can be 0.01 L / h, 0.02 L / h, 0.03 L / h, 0.04 L / h, 0.05 L / h, 0.06 L / h, 0.07 L / h, 0.08 L / h, 0.09 L / h, 0.1 L / h, 0.11 L / h, 0.12 L / h, 0.13 L / h, 0.14 L / h, 0. The preferred flow rates are 15 L / h, 0.16 L / h, 0.17 L / h, 0.18 L / h, 0.19 L / h, 0.2 L / h, 0.21 L / h, 0.22 L / h, 0.23 L / h, 0.24 L / h, 0.25 L / h, 0.26 L / h, 0.27 L / h, 0.28 L / h, 0.29 L / h, 0.3 L / h, and any two of these values, preferably within the range of 0.03-0.12 L / h. This preferred embodiment appropriately increases the hydroxyl content of alumina, which is beneficial for stabilizing the alumina framework structure.

[0051] According to the present invention, preferably, the calcination in step S2 is carried out under oxygen-containing atmosphere and water vapor conditions.

[0052] According to the present invention, preferably, the oxygen-containing atmosphere flow rate relative to 1 kg of modified alumina is 10-200 L / h, for example, it can be 10 L / h, 20 L / h, 30 L / h, 40 L / h, 50 L / h, 60 L / h, 70 L / h, 80 L / h, 90 L / h, 100 L / h, 110 L / h, 120 L / h, 130 L / h, 140 L / h, 150 L / h, 160 L / h, 170 L / h, 180 L / h, 190 L / h, 200 L / h, and any two of these values ​​forming a range, preferably 50-100 L / h. This preferred embodiment is beneficial for improving the chlorine penetration capacity of the gas-phase dechlorinating agent.

[0053] In this invention, the oxygen-containing atmosphere can be a conventional choice in the art, such as air or oxygen.

[0054] The present invention does not particularly limit the conditions for the dechlorination and deoxygenation reaction described in step (1), and can refer to conventional methods in the art. Preferably, the conditions for the dechlorination and deoxygenation reaction described in step (1) include: a temperature of 200-400℃, preferably 280-350℃; a pressure of 3-15MPa, preferably 5-8MPa; and a liquid hourly space velocity of 0.1-10h. -1 Preferably 0.5-2h -1 The hydrogen-to-oil volume ratio is 300-3000, preferably 800-1200.

[0055] The present invention does not have any particular requirements for the type of hydrodeoxygenation catalyst, and any conventional choice in the art can be used. It can be prepared by conventional methods in the art, or it can be obtained commercially, and will not be described in detail here.

[0056] The purpose of the gas-liquid separation in step (1) of this invention is to fully separate the hydrogen chloride contained in the liquid phase and transfer it to the gas phase to obtain gas phase stream W; subsequently, the gas phase stream W is contacted with the gas phase dechlorinating agent to perform adsorption dechlorination under gas phase conditions, which is beneficial to improve the adsorption efficiency and penetration capacity of the gas phase dechlorinating agent.

[0057] Preferably, the liquid phase material obtained by gas-liquid separation in step (1) is a refined oil heavy fraction.

[0058] The gas-liquid separation in step (1) of this invention can be performed using conventional methods in the art. Preferably, the gas-liquid separation in step (1) is carried out in a high-pressure stripping tower. Using this preferred embodiment, hydrogen chloride is dispersed in the gas phase through stripping, which is beneficial for subsequent removal of hydrogen chloride.

[0059] Preferably, the operating conditions of the high-pressure stripping tower include: pressure of 0.5-20 MPa, preferably 1-12 MPa; tower top temperature of 180-300℃, preferably 200-260℃; and tower bottom temperature of 250-500℃, preferably 280-350℃.

[0060] The present invention has a wide range of choices for the stripping gas introduced into the high-pressure stripping tower. Preferably, the stripping gas introduced into the high-pressure stripping tower is selected from at least one of hydrogen, nitrogen and water vapor.

[0061] Preferably, the mass fraction of the stripping gas feed rate to the high-pressure stripping tower feed rate is 0.1-15%.

[0062] In this invention, the feed to the high-pressure stripping tower refers to the reaction product of the dechlorination and deoxygenation reaction in step (1).

[0063] According to the present invention, preferably, the conditions for adsorption dechlorination in step (2) include: a temperature of 200-350℃, preferably 250-300℃; a pressure of 3-15MPa, preferably 5-8MPa; and a volume hourly space velocity of 0.1-10h. -1 Preferably 0.5-2h -1 .

[0064] Preferably, the method further includes: separating the adsorption dechlorination reaction product described in step (2) to obtain refined oil light fraction and aqueous solution.

[0065] The present invention does not particularly limit the separation method, and separation methods conventionally used in the art can be adopted, such as using a cold high-pressure separator for separation.

[0066] The method described in this invention is applicable to the treatment of bio-oils with different organochlorine and oxygen contents.

[0067] Preferably, the content of organochlorine in the chlorinated bio-oil is not less than 10 μg / g, and more preferably 50-100 μg / g.

[0068] Preferably, the oxygen content in the chlorinated bio-oil is not higher than 15 wt%.

[0069] Preferably, the organochlorine is derived from chlorinated organic compounds in biological oils, and the chlorinated organic compounds include at least one of chlorinated alkanes, chlorinated alkenes, and chlorinated aromatics.

[0070] The bio-oils described in this invention may also contain sulfur, as well as mechanical impurities such as iron, nickel, vanadium, sodium, and calcium.

[0071] Preferably, the total content of mechanical impurities in the bio-oil is not higher than 0.1 wt%.

[0072] Preferably, the sulfur content in the bio-oil is not higher than 50 mg / kg.

[0073] The present invention has a wide range of choices for the types of chlorinated bio-oil raw materials, which can be chlorinated bio-oils obtained by various methods commonly used in the field.

[0074] Preferably, the hydrodeoxygenation catalyst is sulfided before use; the gas-phase dechlorination agent does not need to be sulfided before use.

[0075] The present invention does not impose any particular limitation on the specific conditions of the vulcanization, and can be carried out with reference to conventional methods in the art.

[0076] The present invention will be described in detail below through embodiments.

[0077] In the following examples, the organic chlorine content was determined by X-ray fluorescence spectroscopy; the inorganic chlorine content was determined by gas chromatography.

[0078] In the following preparation examples, the air flow rate and water vapor flow rate are both relative to 1 kg of modified alumina.

[0079] Preparation Example 1

[0080] 1 kg of boehmite dry adhesive powder, 212.5 g of magnesium oxide, and 30 g of guar gum powder were mixed evenly. Then, 1200 mL of water and 20 mL of nitric acid were added, and the mixture was kneaded and extruded on a twin-screw extruder to obtain butterfly-shaped strips with a diameter of 1.3 mm. The strips were then dried at 120 °C for 3 hours to obtain modified alumina. The modified alumina was then calcined at 500 °C, with an air flow rate of 75 L / h and a steam flow rate of 0.05 L / h for 3 hours to obtain dechlorinating agent A1. Its composition and performance parameters are shown in Table 1.

[0081] Preparation Example 2

[0082] 1 kg of boehmite dry adhesive powder, 206.25 g of sodium oxide, and 30 g of guar gum powder were mixed evenly, and then 1200 mL of aqueous solution and 20 mL of nitric acid were added. The mixture was then kneaded and extruded on a twin-screw extruder to obtain butterfly-shaped strips with a diameter of 1.3 mm. After drying at 120 °C for 3 hours, modified alumina was obtained. The modified alumina was then calcined at 600 °C, with an air flow rate of 50 L / h and a steam flow rate of 0.05 L / h for 3 hours to obtain dechlorination agent A2. Its composition and performance parameters are shown in Table 1.

[0083] Preparation Example 3

[0084] (1) Preparation of modified carrier: 1 kg of boehmite dry adhesive powder, 291.67 g of magnesium oxide, and 30 g of guar gum powder were mixed evenly, and 1200 mL of aqueous solution and 20 mL of nitric acid were added. The mixture was then kneaded and extruded on a twin-screw extruder to obtain a butterfly-shaped strip with a diameter of 1.3 mm. The strip was then dried at 120 °C for 3 hours to obtain modified alumina. The modified alumina was then calcined at 500 °C, with an air flow rate of 100 L / h and a steam flow rate of 0.10 L / h for 3 hours to obtain dechlorination agent A3. Its composition and performance parameters are shown in Table 1.

[0085] Comparative Preparation Example 1

[0086] The preparation method of Example 1 was followed, except that the amount of magnesium oxide was changed so that the magnesium oxide content was 10% by weight based on the total weight of the gas-phase dechlorinating agent, thus obtaining dechlorinating agent D1. Its composition and performance parameters are shown in Table 1.

[0087] Comparative Preparation Example 2

[0088] The preparation method was followed as in Example 1, except that the modified alumina was not calcined under steam conditions. Specifically, the modified alumina was calcined at 500°C in air for 3 hours to obtain the dechlorination catalyst D2. Its composition and performance parameters are shown in Table 1.

[0089] Comparative preparation example 3

[0090] 1 kg of boehmite dry adhesive powder and 30 g of guar gum powder were mixed evenly, then 1200 mL of water and 20 mL of nitric acid were added. The mixture was kneaded and extruded on a twin-screw extruder to obtain butterfly-shaped strips with a diameter of 1.3 mm. The strips were then dried at 120 °C for 3 hours and calcined at 500 °C in air for 3 hours to obtain an alumina carrier. A magnesium nitrate aqueous solution (0.7 g / mL) was then impregnated onto the alumina carrier, dried at 120 °C for 3 hours, and calcined at 500 °C in air for 3 hours. This impregnation-drying-calcination process was repeated once to obtain dechlorination agent D3. Its composition and performance parameters are shown in Table 1.

[0091] Table 1

[0092]

[0093] Note: The content of active metal components is based on the total weight of the gas-phase dechlorination agent;

[0094] A refers to the weight loss rate of the catalyst in the temperature range of 200℃-500℃, as characterized by TGA.

[0095] Example 1

[0096] RS-3100 hydrodeoxygenation catalyst (produced by Changling Catalyst Factory) was loaded into a fixed-bed hydrotreating reactor, and the gas-phase dechlorination agent prepared in Preparation Example 1 was loaded into a gas-phase dechlorination reactor, with each catalyst loading amounting to 100 mL. First, the hydrodeoxygenation catalyst was subjected to programmed temperature sulfidation: straight-run kerosene containing 2% dimethyl disulfide was used as the sulfiding oil, and the temperature was increased from 110°C to 230°C at a rate of 20°C / h and held for 6 h; then, the temperature was increased to 360°C at a rate of 20°C / h and held for 6 h. Hydrogen and chlorinated bio-oil feedstock (composition shown in Table 2) were mixed and then fed into the hydrotreating reactor for hydrodechlorination and hydrodeoxygenation reactions to obtain reaction products. The above reaction products were separated into gas and liquid phases in a high-pressure stripping tower. The liquid phase was the heavy fraction of refined oil, and the gas phase was fed into the dechlorination reactor for adsorption dechlorination. The adsorption dechlorination reaction products were separated by a cold high-pressure separator to obtain the light fraction of refined oil and an aqueous solution.

[0097] The operating conditions for the hydrogenation reactor are as follows: average bed temperature of 320℃, pressure of 6.4 MPa, and liquid hourly space velocity of 1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 1000. The operating conditions of the high-pressure stripping tower are: pressure 6.4 MPa, bottom temperature 350℃, top temperature 260℃, and the stripping gas is hydrogen, with the stripping gas feed rate accounting for 5% of the high-pressure stripping tower feed by mass. The operating conditions of the dechlorination reactor are: average bed temperature 260℃, pressure 6.4 MPa, and gas hourly space velocity (VHSV) 1.0 h⁻¹. -1 .

[0098] The chlorine content of the obtained aqueous solution and oil products (refined oil heavy fraction and refined oil light fraction) was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 h of reaction are shown in Table 3.

[0099] Example 2

[0100] RS-3100 hydrodeoxygenation catalyst (produced by Changling Catalyst Factory) was loaded into a fixed-bed hydrotreating reactor, and the gas-phase dechlorination agent prepared in Preparation Example 2 was loaded into a gas-phase dechlorination reactor, with each catalyst loading amounting to 100 mL. First, the hydrodeoxygenation catalyst was subjected to programmed temperature sulfidation: straight-run kerosene containing 2% dimethyl disulfide was used as the sulfiding oil, and the temperature was increased from 110°C to 230°C at a rate of 20°C / h and held for 6 h; then, the temperature was increased to 360°C at a rate of 20°C / h and held for 6 h. Hydrogen and chlorinated bio-oil feedstock (composition shown in Table 2) were mixed and then fed into the hydrotreating reactor for hydrodechlorination and hydrodeoxygenation reactions to obtain reaction products. The above reaction products were separated into gas and liquid phases in a high-pressure stripping tower. The liquid phase was the heavy fraction of refined oil, and the gas phase was fed into the dechlorination reactor for adsorption dechlorination. The adsorption dechlorination reaction products were separated by a cold high-pressure separator to obtain the light fraction of refined oil and an aqueous solution.

[0101] The operating conditions for the hydrogenation reactor are as follows: average bed temperature of 300℃, pressure of 6.4 MPa, and liquid hourly space velocity of 1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 1000. The operating conditions of the high-pressure stripping tower are: pressure 6.4 MPa, bottom temperature 340℃, top temperature 255℃, and the stripping gas is hydrogen, with the stripping gas feed rate accounting for 8% of the high-pressure stripping tower feed by mass. The operating conditions of the dechlorination reactor are: average bed temperature 270℃, pressure 6.4 MPa, and gas hourly space velocity (VHSV) 1.0 h⁻¹. -1 .

[0102] The chlorine content of the obtained aqueous solution and oil products (refined oil heavy fraction and refined oil light fraction) was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 h of reaction are shown in Table 3.

[0103] Example 3

[0104] RS-3100 hydrodeoxygenation catalyst (produced by Changling Catalyst Factory) was loaded into a fixed-bed hydrotreating reactor, and the gas-phase dechlorination agent prepared in Preparation Example 3 was loaded into a gas-phase dechlorination reactor, with each catalyst loading amounting to 100 mL. First, the hydrodeoxygenation catalyst was subjected to programmed temperature sulfidation: straight-run kerosene containing 2% dimethyl disulfide was used as the sulfiding oil, and the temperature was increased from 110°C to 230°C at a rate of 20°C / h and held for 6 h; then, the temperature was increased to 360°C at a rate of 20°C / h and held for 6 h. Hydrogen and chlorinated bio-oil feedstock (composition shown in Table 2) were mixed and then fed into the hydrotreating reactor for hydrodechlorination and hydrodeoxygenation reactions to obtain reaction products. The above reaction products were separated into gas and liquid phases in a high-pressure stripping tower. The liquid phase was the heavy fraction of refined oil, and the gas phase was fed into the dechlorination reactor for adsorption dechlorination. The adsorption dechlorination reaction products were separated by a cold high-pressure separator to obtain the light fraction of refined oil and an aqueous solution.

[0105] The operating conditions for the hydrogenation reactor are as follows: average bed temperature of 340℃, pressure of 6.4 MPa, and liquid hourly space velocity of 1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 1000. The operating conditions for the high-pressure stripping tower are: pressure 6.4 MPa, bottom temperature 320°C, top temperature 250°C, and the stripping gas is hydrogen, with the stripping gas feed rate accounting for 10% of the total feed to the high-pressure stripping tower. The operating conditions for the dechlorination reactor are: average bed temperature 250°C, pressure 6.4 MPa, and gas hourly space velocity (VHSV) 1.0 h⁻¹. -1 .

[0106] The chlorine content of the obtained aqueous solution and oil products (refined oil heavy fraction and refined oil light fraction) was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 h of reaction are shown in Table 3.

[0107] Comparative Example 1

[0108] The procedure was carried out according to Example 1, except that the gas-phase dechlorinating agent D1 prepared in Comparative Preparation Example 1 was used instead.

[0109] The chlorine content of the obtained aqueous solution and oil products (refined oil heavy fraction and refined oil light fraction) was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 h of reaction are shown in Table 3.

[0110] Comparative Example 2

[0111] The procedure was carried out according to Example 1, except that the gas-phase dechlorinating agent D2 prepared in Comparative Preparation Example 2 was used instead.

[0112] The chlorine content of the obtained aqueous solution and oil products (refined oil heavy fraction and refined oil light fraction) was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 h of reaction are shown in Table 3.

[0113] Comparative Example 3

[0114] The procedure was carried out according to Example 1, except that the gas-phase dechlorinating agent D3 prepared in Comparative Preparation Example 3 was used instead.

[0115] The chlorine content of the obtained aqueous solution and oil products (refined oil heavy fraction and refined oil light fraction) was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 h of reaction are shown in Table 3.

[0116] Comparative Example 4

[0117] The procedure was carried out according to Example 1, except that the dechlorination catalyst prepared in Example 1 was replaced with an RCL-type gas-phase dechlorination catalyst (from the China Petroleum & Chemical Research Institute).

[0118] The chlorine content of the obtained aqueous solution and oil products (refined oil heavy fraction and refined oil light fraction) was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 h of reaction are shown in Table 3.

[0119] Comparative Example 5

[0120] The chlorinated bio-oil first undergoes hydrodechlorination and hydrodeoxygenation reactions in a fixed-bed hydrotreating reactor. The hydrotreating reactor is loaded with a 100 mL hydrodeoxygenation catalyst, RS-3100 (produced by Changling Catalyst Factory). Then, it undergoes adsorption dechlorination in a dechlorination reactor, which is loaded with the gas-phase dechlorinating agent prepared in Example 1, also with a 100 mL catalyst loading. Finally, the reaction products are separated in a cold high-pressure separator to obtain an aqueous solution and the oil product. The operating conditions of the hydrotreating reactor are: average bed temperature of 320℃, pressure of 6.4 MPa, and liquid hourly space velocity of 1.0 h⁻¹. -1 The hydrogen-to-oil ratio was 1000; the operating conditions of the dechlorination reactor were: average bed temperature of 260℃, pressure of 6.4MPa, and liquid hourly space velocity of 1.0 h⁻¹. -1 The hydrogen-to-oil ratio is 1000.

[0121] The chlorine content of the obtained aqueous solution and oil was analyzed, and the crushing strength before and after the dechlorination agent reaction was analyzed. The results after 500 hours of reaction are shown in Table 3.

[0122] Table 2

[0123]

[0124]

[0125] Table 3

[0126]

[0127] Note: The chlorine content of light and heavy fractions of refined oil mainly refers to the organic chlorine content, which reflects the dechlorination activity of the hydrodeoxygenation catalyst; the chlorine content in aqueous solution mainly refers to the HCl content, which reflects the chlorine adsorption activity of the gas-phase dechlorination agent.

[0128] Change in crushing strength of dechlorinating agent = (crushing strength of fresh agent - crushing strength of dechlorinating agent after reaction) / crushing strength of fresh agent × 100%.

[0129] As can be seen from the results in Table 3, compared with the comparative example, the dechlorination method of this invention results in a chlorine content of <1 mg / L in both heavy and light distillate oils after dechlorination, and a chlorine content of <1 mg / L in the aqueous solution. This indicates that the method of this invention can efficiently remove chlorine from bio-oils and effectively solve the problem of chloride ion corrosion of the equipment during bio-oil processing. In addition, the change in crushing strength of the gas-phase dechlorinating agent of this invention before and after the reaction is <10%, indicating that the gas-phase dechlorinating agent of this invention has good mechanical strength and structural stability in the harsh environment of high temperature, high pressure, and high concentration of water vapor, effectively extending the operating cycle of the dechlorination reactor.

[0130] Compared with the gas-phase dechlorinating agents provided in the embodiments of the present invention, although the dechlorinating agent described in Comparative Example 1 has better structural stability and mechanical strength, its low chlorine penetration capacity means that after 500 hours of operation, the hydrogen chloride generated by the hydrogenation reaction penetrates the dechlorinating agent bed, causing a significant increase in the hydrogen chloride content in the aqueous solution. Although the dechlorinating agent described in Comparative Example 2 has a high chlorine penetration capacity, its poor structural stability leads to a significant decrease in the crushing strength of the dechlorinating agent after the reaction, resulting in a decrease in the dechlorinating agent's chlorine adsorption capacity after 500 hours of reaction and an increase in the chlorine content in the aqueous solution, which is detrimental to the long-term operation of the device. Due to its low chlorine penetration capacity and poor structural stability, the dechlorinating agent described in Comparative Example 3 also exhibits a decrease in chlorine adsorption capacity after 500 hours of reaction, leading to an increase in the chlorine content in the aqueous solution. The RCL dechlorinating agent described in Comparative Example 4 shows a significant decrease in crushing strength after the reaction, with some of the discharged agent breaking or even pulverizing, resulting in a significant decrease in the dechlorinating agent's chlorine adsorption capacity, which adversely affects the long-term operation of the device. In the dechlorination method described in Comparative Example 5, since the hydrogenation reactor and the dechlorination reactor are connected in series, and a high-pressure stripping tower is not used to separate the gas and liquid phases of the reaction products of the hydrogenation reactor, the dechlorinating agent is in a two-phase reaction environment, resulting in a low chlorine capacity of the dechlorinating agent and a high chlorine content in the aqueous solution after the reaction, which exposes the device to a greater risk of corrosion.

[0131] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for dechlorination of a chlorinated bio-oil, characterized by, The method comprises the following steps: (1) carrying out dechlorination and deoxygenation reaction of the chlorinated biological oil with hydrogen under the action of a hydrodeoxygenation catalyst, and then carrying out gas-liquid separation to obtain a gas phase stream W; (2) carrying out adsorption dechlorination of the gas phase stream W under the action of a gas phase dechlorination agent; The gas phase dechlorination agent comprises alumina and an active metal component; the active metal component is selected from at least one of alkali metals and alkaline earth metals; the content of the active metal component, calculated as an oxide, is 20-35% by weight based on the total weight of the gas phase dechlorination agent; The weight loss rate of the gas phase dechlorination agent in the temperature range of 200-500°C is 10-25% according to TGA characterization.

2. The method according to claim 1, wherein The weight loss rate of the gas phase dechlorination agent in the temperature range of 200-500°C is 10-20% according to TGA characterization; Preferably, the content of the active metal component, calculated as an oxide, is 20-30% by weight based on the total weight of the gas phase dechlorination agent; Preferably, the alkali metal is sodium and / or potassium, preferably sodium; Preferably, the alkaline earth metal is magnesium and / or calcium, preferably magnesium.

3. The method according to claim 1 or 2, wherein The breakthrough chlorine capacity of the gas phase dechlorination agent is not less than 20%, preferably 20-30%; Preferably, the specific surface area of the gas-phase dechlorinating agent is 150-230 cm 2 / g, and the pore volume is 0.5-0.7 cm 3 / g; Preferably, the crushing strength of the gas phase dechlorination agent is 15-35 N / mm, preferably 20-30 N / mm; Preferably, the gas phase dechlorination agent does not have a spinel structure.

4. The method of any of claims 1-3, wherein, The preparation method of the gas phase dechlorination agent comprises the following steps: S1, mixing and forming alumina precursor and active metal component precursor, and then drying to obtain modified alumina; S2, calcining the modified alumina obtained in step S1 under water vapor conditions.

5. The method according to claim 4, wherein The mass ratio of the alumina precursor to the active metal component precursor is 1-8:1, preferably 2-5:1; wherein the active metal component precursor is calculated as an active metal component oxide; Preferably, the forming in step S1 is selected from at least one of extrusion forming, spray forming, rolling forming and tabletting forming; Preferably, the drying in step S1 is under conditions comprising a temperature of 60-280°C, preferably 110-200°C, and a time of 1-48 hours, preferably 2-12 hours.

6. The method according to claim 4 or 5, wherein The calcining in step S2 is under conditions comprising a temperature of 300-600°C, preferably 350-600°C, and a time of 1-10 hours, preferably 2-8 hours; Preferably, the water vapor flow is 0.01-0.3 L / h, preferably 0.03-0.12 L / h, per 1 kg of modified alumina; Preferably, the calcining in step S2 is carried out under an oxygen-containing atmosphere and water vapor conditions; Preferably, the oxygen-containing atmosphere flow is 10-200 L / h, preferably 50-100 L / h, per 1 kg of modified alumina.

7. The method according to any one of claims 1-6, wherein The conditions of the dechlorination and deoxygenation reaction in step (1) include: temperature of 200-400℃, preferably 280-350℃; pressure of 3-15 MPa, preferably 5-8 MPa; liquid hourly space velocity of 0.1-10 h -1 , preferably 0.5-2 h -1 ; hydrogen to oil volume ratio of 300-3000, preferably 800-1200.

8. The method according to any one of claims 1-7, wherein The gas-liquid separation in step (1) is carried out in a high-pressure stripping column; Preferably, the operating conditions of the high-pressure stripping column include: pressure of 0.5-20 MPa, preferably 1-12 MPa; overhead temperature of 180-300℃, preferably 200-260℃; bottom temperature of 250-500℃, preferably 280-350℃; Preferably, the stripping gas introduced into the high-pressure stripping column is at least one selected from hydrogen, nitrogen and water vapor; Preferably, the mass fraction of the stripping gas feed amount in the high-pressure stripping column feed amount is 0.1-15%.

9. The method according to any one of claims 1-8, wherein, The conditions for the adsorptive dechlorination in step (2) include: temperature of 200-350°C, preferably 250-300°C; pressure of 3-15 MPa, preferably 5-8 MPa; volume space velocity of 0.1-10 h -1 , preferably 0.5-2 h -1 .

10. The method according to any one of claims 1-9, wherein, The content of organic chlorine in the chlorinated bio-oil is not less than 10 μg / g, preferably 50-100 μg / g; Preferably, the oxygen content in the chlorinated bio-oil is not higher than 15 wt%.

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