Methods for disposing of waste cooking oil

Abstract

This invention discloses a method for treating waste edible oils. The method includes: providing a hydrogenation catalyst, comprising a support and an active metal oxide coated on its surface; mixing the hydrogenation catalyst with a catalytic slurry and waste edible oil to form a slurry hydrogenation bed; and conducting a hydrogenation reaction in the slurry hydrogenation bed under a reducing atmosphere. The method provided by this invention uses a mixed feed of waste edible oil and catalytic slurry for catalytic hydrogenation, which can obtain a distillate oil-liquid phase product with a continuous carbon number distribution and uniform hydrocarbon content, suitable for use as feed to a fixed-bed hydrogenation unit. It effectively avoids problems such as catalyst sintering and deactivation caused by overheating due to concentrated exothermic reactions in the fixed-bed hydrogenation reaction zone caused by excessively high content of a single component, thus ensuring stable operation of the reaction unit. It directly and simultaneously solves two major problems: the difficulty in stably hydrogenating waste edible oils and the high cost of catalytic slurry hydrogenation, and has good application prospects.

Description

Technical Field

[0001] This invention relates to the field of catalytic hydrogenation technology, particularly to the processing methods of inferior heavy oil, and especially to a method for treating waste edible oil. Background Technology

[0002] China is a major catering country, producing a large amount of waste cooking oil, approximately 4-8 million tons annually. Of this, about 4 million tons can be reused, leaving a considerable amount of waste cooking oil for which better applications need to be explored.

[0003] Currently, there is a lot of research on the reuse of waste cooking oil abroad, such as using waste fish oil and soybean oil to produce biofuel through pyrolysis, and using olive oil to produce bio-oil through catalytic pyrolysis. Domestic research mainly focuses on turning waste cooking oil into bio-lubricating oil, as well as methyl esterification to convert it into biofuel oil.

[0004] For example, Chinese invention patent CN103756794A discloses a method for producing biodiesel by hydrogenating waste edible oils. This method uses a fixed bed or fluidized bed hydrogenation process, rather than a slurry bed hydrogenation process.

[0005] On the other hand, catalytic slurry is the residual oil discharged from the catalytic cracking unit of an oil refinery. It typically contains more than 30% saturated hydrocarbons, more than 50% aromatics, and about 10% gums and asphaltenes, as well as a small amount of catalytic cracking catalyst dust. Because it is a product of the catalytic cracking process, it was previously treated as waste, hence the name catalytic external slurry.

[0006] Currently, the processing of low-quality heavy oils such as catalytic slurry oil and residual oil involves two main processes: decarbonization and hydrotreating. The former primarily includes coking and solvent deasphalting processes; the latter mainly includes three process types: fixed-bed, fluidized-bed, and suspended-bed. Coking and hydrotreating are widely used heavy oil processing technologies. Coking can process high-sulfur, high-metal, and high-carbon residual oils and some catalytic slurry oils; however, due to the generation of large amounts of gas and low-quality coke, it suffers from low liquid product yields and poor overall economic efficiency, making it difficult to achieve efficient utilization of catalytic slurry oils.

[0007] Currently, catalytic slurry is generally sold as heavy fuel oil. This results in low added value and resource waste. Other uses include: blending as feedstock for delayed coking units; catalytic slurry with a catalyst dust content of less than or equal to 100 μg / g and low sulfur content can be used to prepare needle coke; or for the preparation of carbon fibers, reinforcing distillation agents, asphalt blending components, and rubber additives. These applications generally suffer from problems such as low raw material utilization, environmental pollution, or low overall economic efficiency.

[0008] Slurry-bed hydrotreating is a green chemical process that can process low-quality heavy oils such as catalytic slurry. Early German VCC processes used lignite and blast furnace ash as additives for slurry-bed hydrotreating. The related HDH / HDHPLUS process used coal and refractory minerals as additives. In the 1990s, Japanese companies such as Asahi, Nippon Mining, and Chiyoda developed the SOC process, using molybdenum compounds and carbon black as catalysts. The Canadian CANMET process uses sub-bituminous coal, lignite loaded with ferric sulfate, or other metals as catalysts. HC and EST technologies use oil-soluble catalysts. China University of Petroleum and Dow Chemical Company use water-soluble catalysts.

[0009] Specifically, Chinese invention patent CN106622268A discloses a slurry-bed hydrogenation catalyst with silica-alumina and alumina as supports, iron, calcium and molybdenum as active metals, and an oxide content of 10wt%-40wt%, with a maximum feed conversion rate of 91.2%; CN105771992A uses ferrous sulfate from titanium dioxide waste and alkaline solution to prepare a slurry-bed hydrogenation catalyst with a heavy oil conversion rate of over 50%; CN113145106A describes a transition metal tungsten catalyst supported on carbonaceous particles, which has a simple synthesis process and good feed adaptability; CN107670699A uses semi-coke pore-expanding material, molecular sieve and catalytic cracking waste catalyst as composite supports to obtain a slurry-bed hydrogenation catalyst.

[0010] However, the single oil treatment methods in the above-mentioned existing technologies all face problems such as low catalytic efficiency, poor treatment effect, and easy deactivation of catalysts. There are no reports on the co-treatment of catalytic oil slurry and waste edible oil in the existing technologies. Summary of the Invention

[0011] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for treating waste cooking oil.

[0012] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0013] In a first aspect, the present invention provides a method for treating waste cooking oil, comprising:

[0014] A hydrogenation catalyst is provided, the hydrogenation catalyst comprising a support and an active metal oxide coated on the surface of the support;

[0015] The hydrogenation catalyst is mixed with catalytic oil slurry and waste edible oil to form a slurry hydrogenation bed.

[0016] The hydrogenation reaction is carried out in the slurry hydrogenation bed under a reducing atmosphere containing hydrogen.

[0017] Based on the above technical solution, compared with the prior art, the beneficial effects of the present invention include at least the following:

[0018] The waste edible oil treatment method provided by this invention uses a mixed feed of waste edible oil and catalytic slurry oil for catalytic hydrogenation. This yields a distillate oil liquid phase product with a continuous carbon number distribution and uniform hydrocarbon content, suitable for use as feed to a fixed-bed hydrogenation unit. The catalytic hydrogenation products of waste edible oil and catalytic slurry oil overlap in their distillation ranges. Furthermore, the former has a higher saturated hydrocarbon content, while the latter has a higher aromatic hydrocarbon content. This mutual complementarity effectively avoids problems such as catalyst sintering and deactivation caused by overheating due to concentrated exothermic reactions in the fixed-bed hydrogenation reaction zone caused by excessively high content of any single component. This ensures more stable operation and ease of operation of the reaction unit. Simultaneously, because the alkane content in the fixed-bed hydrogenation feed is moderate, diesel products with a cetane number that meets the standard but is not excessively high can be obtained. This directly solves two major problems simultaneously: the difficulty in stable hydrogenation of waste edible oil and the high cost of catalytic slurry oil hydrogenation, demonstrating promising application prospects.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to enable those skilled in the art to better understand the technical means of this application and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below. Detailed Implementation

[0020] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0021] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0022] This invention provides a method for treating waste cooking oil, comprising the following steps:

[0023] A hydrogenation catalyst is provided, the hydrogenation catalyst comprising a support and an active metal oxide coated on the surface of the support.

[0024] The hydrogenation catalyst is mixed with catalytic slurry and waste edible oil to form a slurry hydrogenation bed.

[0025] The hydrogenation reaction is carried out in the slurry hydrogenation bed under a reducing atmosphere containing hydrogen.

[0026] The catalytic slurry refers to the byproduct generated during the catalytic cracking of heavy oil in the petrochemical industry, also known as catalytic external slurry; the waste edible oil refers especially to the waste edible oil from the catering industry, also known as waste edible oil.

[0027] In some embodiments, the mass ratio of waste edible oil to catalytic slurry in the slurry hydrogenation bed is 1:1 to 1:9.

[0028] In some embodiments, the carrier may include metallurgical powder, and in some embodiments, it is preferably ferrometallurgical powder.

[0029] In some embodiments, the active metal oxide may include molybdenum oxide.

[0030] In some embodiments, the active metal oxide may include molybdenum trioxide.

[0031] In some embodiments, the mass fraction of the active metal oxide in the hydrogenation catalyst may be 1-3%.

[0032] In some embodiments, the particle size of the hydrogenation catalyst can be 80-100 μm.

[0033] In some embodiments, the hydrogenation catalyst can be prepared by the following method:

[0034] 1) The carrier is treated with a solution of naphthyl surfactant to obtain a modified carrier.

[0035] 2) React the active metal salt with ammonia water to generate active metal crystals.

[0036] 3) Mix the modified support with the active metal crystal and react to obtain an active support mixture.

[0037] 4) The active support mixture is calcined and pulverized to obtain the hydrogenation catalyst.

[0038] Treating the support with a naphthyl surfactant effectively reduces the surface viscosity of the support and the interfacial tension between it and the active metal crystals, resulting in more uniform mixing and better complexation. Simultaneously, the benzopyrene structure in the naphthyl surfactant is similar to the polycyclic aromatic hydrocarbon components in the catalytic slurry and the benzopyrene components in waste edible oils, effectively improving the compatibility between the catalyst and the raw materials. Since the catalytic slurry serves as both a reactant and a solvent for the waste edible oils, this good compatibility allows for more uniform contact between the catalyst and the dissolved waste edible oil components, increasing the effective catalytic contact area and better promoting the adsorption of reactant molecules on the catalyst surface. This significantly reduces the heat of adsorption and allows the catalyst to exhibit better catalytic performance. For waste edible oils, this leads to a significant increase in their conversion rate.

[0039] As a typical implementation example of the above technical solution, the processing method can be implemented through the following steps:

[0040] First, metallurgical powder is impregnated with an aqueous solution of sodium naphthyl sulfonate. This impregnated material is then mixed evenly with an active metal crystal precipitate, and finally dried, baked, pulverized, and sieved to obtain the slurry bed hydrogenation catalyst of this invention. Using this catalyst, waste edible oil and catalytic oil mixture are subjected to slurry bed hydrogenation reaction to obtain combustible gas, liquid phase products, and a small amount of coke. The liquid phase products with a dry point of less than 520°C are used as feed for fixed bed hydrogenation units to produce clean gasoline and diesel products.

[0041] Its specific implementation steps can be divided into:

[0042] S1. Take a certain mesh size of metallurgical powder, impregnate it with sodium naphthyl sulfonate aqueous solution, mix it evenly and set aside for use;

[0043] S2. Dissolve a certain amount of ammonium molybdate tetrahydrate in deionized water to obtain an aqueous solution of ammonium molybdate.

[0044] S3. Add ammonia water dropwise to the product of step S2 and stir until homogeneous to obtain a mixture of metal crystal precipitates.

[0045] S4. Add the product from step S1 to the mixture obtained in step S3, and mix evenly by magnetic stirring to obtain a molybdenum-loaded metallurgical powder mixture.

[0046] S5. The product from step S4 is dried, calcined, pulverized, and sieved to obtain a slurry-bed hydrogenation catalyst.

[0047] The metallurgical powder mentioned in step S1 is an iron-based metallurgical powder with a particle size of 200-250 mesh. The volume ratio of the iron metallurgical powder to the sodium naphthyl sulfonate aqueous solution is 1:1, the impregnation temperature is room temperature, and the impregnation time is 30-150 min.

[0048] In step S2, the dissolution temperature is 20-40℃; in step S3, the ammonia concentration is 5%-10%, the dropping temperature is room temperature (unless otherwise specified, room temperature refers to 15-30℃), the dropping rate is 1-5 ml / s per liter of active metal salt aqueous solution, and the amount of ammonia added is the same as the volume of the metal aqueous solution; in step S4, the addition rate is 1-5 g / s per liter of active metal crystal mixture, the magnetic stirrer speed is 600 r / min, and the magnetic stirring is performed for 0.5-1 h; in step S5, the drying and calcination are carried out under normal pressure at 120℃ for 5-8 h, followed by calcination at 260℃ for 5-8 h; the pulverization is carried out using a pulverizer to pulverize to a particle size of 160-180 mesh and sieve to obtain the slurry bed hydrogenation catalyst of this invention with a particle size of 80-100 μm.

[0049] In some embodiments, in step 1), the volume ratio of the carrier to the naphthyl surfactant solution can be 1:1 to 1:2.

[0050] In some implementations, the processing time in step 1) can be 30-150 minutes.

[0051] In some implementations, step 2) may specifically include: adding ammonia dropwise to an aqueous solution of the active metal salt to initiate a reaction.

[0052] In some embodiments, the mass concentration of the ammonia water can be 5-10%, and the dripping rate can be 1-5 ml / s.

[0053] In some implementations, step 3) may specifically include: adding the modified carrier to a mixture of active metal crystals.

[0054] In some embodiments, the addition rate of the modified carrier can be 1-5 g / s, and the reaction time in step 3) can be 0.5-1 h.

[0055] In some implementations, in step 4), the roasting temperature can be 260℃-300℃ and the time can be 5-8h.

[0056] In some embodiments, the slurry hydrogenation bed may also include sulfur.

[0057] In some embodiments, the hydrogenation catalyst in the slurry hydrogenation bed may account for 0.1-0.5% of the total mass of the catalytic slurry and waste edible oil.

[0058] In some embodiments, the hydrogenation catalyst may comprise 70-100% of the total mass of sulfur.

[0059] In some embodiments, the hydrogenation reaction can be carried out at a temperature of 400-450°C, a pressure of 10-25 MPa, and a time of 30-60 min.

[0060] In some embodiments, during the heating process before the hydrogenation reaction, the heating rate can be less than 50°C / h within a temperature range of 200-250°C. The purpose of this setting is to ensure that the sulfidated active metal has higher catalytic efficiency than the unsulfidated active metal oxide. Within a specific temperature range, a reduced heating rate allows for a sufficient sulfidation reaction between the sulfur and the active metal oxide, thereby improving the catalyst's catalytic efficiency.

[0061] As some typical application examples of the above technical solutions, when using the above-mentioned slurry bed hydrogenation catalyst to carry out slurry bed hydrogenation reaction on a mixed feed of waste edible oil and catalytic oil slurry, sulfur powder can also be added at the same time as the mixed feed. The amount of slurry bed hydrogenation catalyst added to the mixed feed is 0.1wt%-0.5wt%, and the amount of sulfur powder added is 70wt%-100wt%. The mass ratio of waste edible oil to catalytic oil slurry is 1:1-1:9.

[0062] The slurry-bed hydrogenation process conditions are as follows: reaction temperature can be 400-450℃, reaction pressure can be 10.0-25.0MPa, stirring rate can be 300r / min, heating rate is 50℃ / h in the 200-250℃ range and 200℃ / h in the 250-450℃ range, and the reaction time is 30-60min after reaching the reaction temperature.

[0063] After separation, the slurry-bed hydrogenation products yield gaseous, liquid, and solid three-phase products. The gaseous product can be used as fuel gas, while the small amount of unconverted components containing the slurry-bed hydrogenation catalyst constitutes the solid phase product. After burning off the carbon deposits on its surface with air, the resulting iron metallurgical powder can still be used as a component of the slurry-bed hydrogenation catalyst of this invention, allowing for recycling. The resulting liquid phase product, with a dry point below 520°C, can be used as feedstock for a fixed-bed hydrogenation unit to further produce clean gasoline and diesel products. Furthermore, the fixed-bed hydrogenation unit generally refers to a hydrocracking unit in an oil refinery.

[0064] Based on the above exemplary technical solutions, this invention provides a method for treating waste edible oils, which are then processed together with catalytic slurry oil and the catalyst provided by this invention through a slurry-bed hydrogenation process. This invention utilizes the complementary composition of waste edible oils and catalytic slurry oil, resulting in a significantly higher alkane content in the liquid-phase product of slurry-bed hydrogenation compared to feedstocks containing only catalytic slurry oil. For the hydrogenation of waste edible oils to produce biodiesel, the cetane number of the product is often very high, generally exceeding 65. Such a high index is considered excessive for diesel engines (the current maximum cetane number for National IV diesel products is 49). In contrast, catalytic slurry oil, due to its high aromatic content, produces fewer alkanes in its hydrogenation liquid-phase product. Thus, by combining the strengths of both, the cetane number of the diesel product obtained after fixed-bed hydrogenation is neither too high nor too low, precisely meeting the requirements of National VI diesel standards. Besides product complementarity, the synergistic combination of waste edible oil and catalytic slurry can effectively avoid catalyst sintering and deactivation caused by overheating due to concentrated exothermic reactions in the fixed-bed hydrogenation reaction zone caused by excessive content of a single component. This ensures more stable and easier operation of the reactor. For example, when using only waste edible oil as feed, even with the same catalyst and hydrogenation conditions, excessive content of a single component can easily lead to rapid catalyst sintering and deactivation due to concentrated exothermic reactions. This ultimately results in incomplete reaction of the waste edible oil, leading to a low conversion rate.

[0065] Therefore, this invention creatively treats two types of waste oils that are difficult to process in a synergistic manner, making their properties complementary and synergistically catalyzing each other, thus achieving the effect of "treating waste with waste".

[0066] Furthermore, in some preferred embodiments, the slurry-bed hydrogenation catalyst prepared by this invention uses ferrometallurgical powder with small and uniform particle size as a support. This small and uniform support particle size provides a larger surface area and more uniform active sites for the reactant molecules, giving the catalyst the characteristics of low active metal loading but high activity. On the other hand, it also provides more deposition sites for large, unreactable molecules in the feedstock, such as gums and asphaltenes, allowing them to leave the reaction system with the catalyst, thereby promoting the reaction and improving the feedstock conversion rate. In addition, the ferrometallurgical powder discharged from the reactor along with the unconverted components can be recycled by burning off its surface carbon deposits and reused as a slurry-bed hydrogenation catalyst support, which is beneficial for reducing carbon emissions. This invention employs a slurry-bed hydrogenation process to convert harmful waste edible oils and refining byproduct catalytic slurry into high-value-added clean gasoline and diesel products, which is beneficial for improving the overall economic efficiency of related enterprises.

[0067] The technical solution of the present invention will be further described in detail below through several embodiments. However, the selected embodiments are only used to illustrate the present invention and do not limit the scope of the present invention.

[0068] The iron metallurgical powder used in the following examples is Jindeshuo brand iron powder produced by Zhengzhou Jindeshuo Metal Materials Co., Ltd., with a density of 5.8-7.2 g / cm3. The selected iron powder has a particle size of 200 mesh, 230 mesh, 240 mesh and 250 mesh, which means the iron powder particle size is 75μm, 62μm, 61μm and 58μm respectively.

[0069] The following embodiments use a WFS-250 micro pulverizer manufactured by Wuxi Jiangyin Xin'an Powder Equipment Co., Ltd. to obtain particles with a particle size of 80-100μm.

[0070] It should be noted that the manufacturers and brands of the raw materials and equipment mentioned above are for illustrative purposes only and are not absolute restrictions on the source of raw materials / equipment.

[0071] Examples 1-4 below illustrate the preparation process of catalysts for slurry-bed hydrogenation.

[0072] Example 1

[0073] 1. At 30℃, 250g of 200-mesh metallurgical powder is impregnated with 42ml of sodium butylnaphthalene sulfonate aqueous solution and mixed evenly for later use.

[0074] 2. Take 1.3 g of ammonium molybdate tetrahydrate, dissolve it in 42 ml of deionized water at 30℃ to obtain an aqueous solution of ammonium molybdate;

[0075] 3. At 30℃, add 42 ml of 5% ammonia solution dropwise at a rate of 0.042 ml / s to the aqueous solution obtained in step 2 to obtain a molybdenum-containing precipitate;

[0076] 4. Add the powder obtained in step 1 to the product obtained in step 3 at an addition rate of 0.042 g / s, and stir magnetically for 0.5 h at a magnetic stirrer speed of 600 r / min to obtain a molybdenum-loaded metallurgical powder mixture.

[0077] 5. The mixture obtained in step 4 is dried at 120°C for 8 hours, then calcined at 260°C for 7 hours, and finally pulverized to 160 mesh particles to obtain this slurry bed hydrogenation catalyst A, which has an active metal content of 1.0 wt% as oxide and a particle size of 96 μm.

[0078] Example 2

[0079] 1. At 20℃, 500g of 230-mesh metallurgical powder is impregnated with 168ml of sodium butylnaphthalene sulfonate aqueous solution and mixed evenly for later use.

[0080] 2. Take 2.5 g of ammonium molybdate tetrahydrate and dissolve it in 84 ml of deionized water at 20 °C to obtain an aqueous solution of ammonium molybdate;

[0081] 3. At 20℃, add 84 ml of 7% ammonia solution dropwise to the aqueous solution obtained in step 2 at a rate of 0.168 ml / s to obtain a molybdenum-containing precipitate.

[0082] 4. Add the powder obtained in step 1 to the product obtained in step 3 at an addition rate of 0.168 g / s, and stir magnetically for 0.6 h at a magnetic stirrer speed of 600 r / min to obtain a molybdenum-loaded metallurgical powder mixture.

[0083] 5. The mixture obtained in step 4 is dried at 120°C for 7 hours, then calcined at 300°C for 6 hours, and finally pulverized to 170 mesh particles to obtain this slurry bed hydrogenation catalyst B, which has an active metal content of 2.0 wt% as oxide and a particle size of 90 μm.

[0084] Example 3

[0085] 1. At 25℃, 900g of 240-mesh metallurgical powder is impregnated with 130ml of sodium butylnaphthalene sulfonate aqueous solution and mixed evenly for later use.

[0086] 2. Take 4.0 g of ammonium molybdate tetrahydrate and dissolve it in 130 ml of deionized water at 25 °C to obtain an aqueous solution of ammonium molybdate;

[0087] 3. At 25℃, add 130 ml of 8% ammonia solution dropwise to the aqueous solution obtained in step 2 at a rate of 0.39 ml / s to obtain a molybdenum-containing precipitate;

[0088] 4. Add the powder obtained in step 1 to the product obtained in step 3 at an addition rate of 0.39 g / s, and stir magnetically for 0.8 h at a magnetic stirrer speed of 600 r / min to obtain a molybdenum-loaded metallurgical powder mixture.

[0089] 5. The mixture obtained in step 4 is dried at 120°C for 6 hours, then calcined at 280°C for 5 hours, and finally pulverized to 180 mesh particles to obtain the slurry bed hydrogenation catalyst C, which has an active metal content of 3.0 wt% as oxide and a particle size of 80 μm.

[0090] Example 4

[0091] 1. At 35℃, 750g of 250-mesh metallurgical powder is impregnated with 218ml of sodium butylnaphthalene sulfonate aqueous solution and mixed evenly for later use.

[0092] 2. Take 3.3 g of ammonium molybdate tetrahydrate and dissolve it in 106 ml of deionized water at 35 °C to obtain an aqueous solution of ammonium molybdate;

[0093] 3. At 35℃, add 106 ml of 10% ammonia solution at a rate of 0.53 ml / s to the aqueous solution obtained in step 2 to obtain a molybdenum-containing precipitate;

[0094] 4. Add the powder obtained in step 1 to the product obtained in step 3 at an addition rate of 0.53 g / s, and stir magnetically for 1.0 h at a magnetic stirrer speed of 600 r / min to obtain a molybdenum-loaded metallurgical powder mixture.

[0095] 5. The mixture obtained in step 4 is dried at 120°C for 5 hours, then calcined at 280°C for 8 hours, and finally pulverized to 175 mesh particles to obtain the slurry bed hydrogenation catalyst D, which has an active metal content of 2.5 wt% as oxide and a particle size of 86 μm.

[0096] The raw materials used for evaluating the activity of the AD catalysts obtained in Examples 1-4 of this invention were waste edible oils provided by a local environmental protection department and catalytic oil slurry provided by a refinery in northern China. Their specific properties are listed in Table 1 below.

[0097] Table 1 Properties of waste edible oils and catalytic oil slurry

[0098]

[0099] The AD catalyst activity evaluation equipment obtained in Examples 1-4 of this invention uses a BS series stirred high-pressure reactor (volume 0.25L, design pressure 35 MPa, design temperature 500℃, stirring speed 0-1500rpm) from Shanghai Laibei Scientific Instrument Co., Ltd., and a SH / T 0165 vacuum distillation apparatus produced by Xi'an Lianxing Experimental Instrument Co., Ltd. is used for hydrogenation product separation.

[0100] The following examples will illustrate the catalytic performance of the catalyst AD prepared in Examples 1-4 above, as well as the synergistic catalytic effect of the catalytic slurry and waste edible oil.

[0101] Examples 5-8

[0102] The AD slurry-bed hydrogenation catalysts obtained in Examples 1-4 were used for slurry-bed hydrogenation of a mixture of waste edible oil and catalytic slurry feedstock. The mass ratio of the two feedstocks and the slurry-bed hydrogenation reaction conditions correspond to Examples 5-8, as detailed in Table 2 below. For the slurry-bed hydrogenation of the waste edible oil and catalytic slurry feedstock, hydrogen gas was first introduced into the reactor to reach a pressure of 25 MPa for leak detection, while simultaneously purging the air from the reactor. Hydrogen gas was then introduced again to reach the reaction pressure, and the temperature was raised to the reaction temperature. After a certain stirring rate and a certain reaction time, heating and stirring were stopped, and the reactor was cooled to room temperature to terminate the reaction. The heating rate in these four examples was 50 °C / h in the 200-250 °C range and 200 °C / h in the 250-450 °C range.

[0103] The sulfur powder used in the experiment was a reagent-grade product. The slurry-bed hydrogenation catalyst's performance in terms of mixed feed and the amount of sulfur powder added are also listed in Table 2.

[0104] After the reaction is complete, the product in the reaction vessel is collected, weighed, and then subjected to vacuum distillation. After distillation, the residue in the distillation flask is washed with toluene, and after centrifugation and drying, coke in the liquid phase is obtained.

[0105] The experimental evaluation indicators include feed conversion rate (i.e., total yield), distillate oil yield, metal removal rate, and coking rate.

[0106] Feed conversion rate = (distillate oil + gas) / feed oil × 100%.

[0107] Distillate oil yield = Distillate oil below 520℃ / Feed oil × 100%.

[0108] Metal removal rate = (1 - metal content in liquid product / metal content in feed oil) × 100%.

[0109] Coking rate = Toluene insoluble matter / Raw material oil × 100%.

[0110] Table 2 Performance evaluation results of slurry bed hydrogenation catalysts in Examples 5-8

[0111]

[0112] As shown in Table 2, the slurry-bed hydrogenation catalyst using inexpensive iron-based metallurgical powder as a carrier in this embodiment of the invention exhibits good catalytic activity when treating low-quality oils—waste edible oils and catalytic slurry. It demonstrates high feed conversion rate and distillate oil yield, along with high total alkane and olefin content in the distillate oil. These high figures indicate that after subsequent fixed-bed hydrogenation, more and better-quality diesel products can be produced, especially with a cetane number reaching the current National VI diesel standard requirement of 49, thus becoming a high-quality diesel product. This improves the economic viability of low-value-added catalytic slurry and environmentally polluting waste edible oils. The high metal removal rate also better protects the activity and stability of the subsequent fixed-bed hydrogenation main catalyst, facilitating long-term operation of the unit and improving its overall economic efficiency. Finally, the coking rate of the above catalytic hydrogenation reaction is less than 1%, indicating that the catalyst of this invention has excellent industrial application prospects. In other words, the industrialization of this invention will generate significant economic and social benefits.

[0113] Comparative Example 1

[0114] This comparative example demonstrates an application of catalytic hydrogenation for treating waste edible oils, as shown below:

[0115] This comparative example is largely the same as Examples 1 and 5, except that the raw material oil is pure waste edible oil, while other proportions and reaction conditions remain unchanged.

[0116] Compared to Example 5, the raw materials were completely replaced with only waste edible oil, while everything else remained unchanged. The resulting raw material conversion rate was 72.6%, the distillate oil yield was 70.5%, and the coking rate was 8.4%. This is significantly worse than the waste edible oil treatment methods provided in Examples 1 and 5 of this invention.

[0117] Comparative Example 2

[0118] This comparative example demonstrates an application of catalytic hydrogenation for treating waste edible oils, as shown below:

[0119] Compared to Example 5, the raw materials were replaced with waste edible oil and catalytic oil slurry at a mass ratio of 2:1, while other aspects remained unchanged. The resulting raw material conversion rate was 84.5%, the distillate oil yield was 81.1%, and the coking rate was 6.8%. This is significantly worse than the waste edible oil treatment methods provided in Examples 1 and 5 of this invention.

[0120] Comparative Example 3

[0121] This comparative example demonstrates an application of catalytic hydrogenation for treating waste edible oils, as shown below:

[0122] Compared to Example 1, in the slurry bed catalyst preparation process, only deionized water was used to soak the metallurgical powder, while other conditions and processes remained unchanged. A comparative catalyst, DC1, was obtained. Then, compared to Example 5, A in Example 5 was replaced with DC1, while other aspects remained the same. The resulting feed conversion rate was 86.9%, the distillate oil yield was 84.7%, and the coke production rate was 5.7%. This is significantly worse than the waste edible oil treatment methods provided in Examples 1 and 5 of this invention.

[0123] Comparative Example 4

[0124] This comparative example demonstrates an application of catalytic hydrogenation for treating waste edible oils, as shown below:

[0125] Compared to Example 1, in the slurry bed catalyst preparation process, sodium butylnaphthalene sulfonate was replaced with sodium butylbenzene sulfonate, while other aspects remained unchanged, resulting in the comparative catalyst DC2. Then, compared to Example 5, A in Example 5 was replaced with DC2, while other aspects remained unchanged. The resulting feed conversion rate was 88.7%, the distillate oil yield was 86.0%, and the coke production rate was 5.0%. This is significantly worse than the waste edible oil treatment methods provided in Examples 1 and 5 of this invention.

[0126] Comparative Example 5

[0127] This comparative example demonstrates an application of catalytic hydrogenation for treating waste edible oils, as shown below:

[0128] Compared to Example 5, the heating rate throughout the entire heating process was 200℃ / h, with other parameters remaining unchanged. The resulting raw material conversion rate was 90.1%, the distillate oil yield was 87.4%, and the coking rate was 4.2%. This is significantly inferior to the waste edible oil treatment methods provided in Examples 1 and 5 of this invention.

[0129] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0130] Based on the above embodiments and comparative examples, it can be clearly stated that: 1. The embodiments of the present invention use iron-based metallurgical powder as a slurry-bed hydrogenation catalyst support, which has significantly higher strength than traditional slurry-bed hydrogenation catalyst supports—such as carbon black, coal powder, blast furnace ash, etc., and is especially suitable for waste edible oil raw materials with high oxygen content. This is because the catalyst will not collapse due to the generation of large amounts of water during hydrogenation, thus giving the catalyst good activity stability, which is beneficial for the hydrogenation reaction of both waste edible oil and catalytic oil slurry. Secondly, the uniform particle size and small particle size of the iron-based metallurgical powder result in a large total surface area within the same volume of catalyst, allowing it to carry more active metals. Furthermore, due to the uniform specifications, the amount of active metal carried per unit volume tends to be consistent, making the catalytic efficiency of the catalyst for inferior heavy oil very uniform in the reactor, effectively reducing the amount of catalyst used while achieving good catalytic effect. Finally, the small and uniformly sized iron powder provides a large and uniform deposition site for large molecular compounds in the raw materials that cannot react. The combined effect of these three aspects demonstrates that the catalyst of the present invention has a low metal loading, good catalytic performance, and good activity stability.

[0131] 2. In this embodiment of the invention, waste edible oil and catalytic slurry are mixed and fed into a hydrogenation reaction to obtain a distillate oil liquid phase product with a continuous carbon number distribution and uniform hydrocarbon content, suitable for use as feedstock in a fixed-bed hydrogenation unit. The two products have overlapping distillation ranges, and the former has a high saturated hydrocarbon content while the latter has a high aromatic hydrocarbon content. This mutual complementarity effectively avoids problems such as catalyst sintering and deactivation caused by overheating in the fixed-bed hydrogenation reaction zone due to concentrated exothermic reactions caused by excessive content of one component. This ensures more stable operation and easier management of the production unit. Simultaneously, because the alkane content in the fixed-bed hydrogenation feedstock is moderate, diesel products with a cetane number that meets the requirements but is not excessively high can be obtained.

[0132] 3. In this embodiment of the invention, a naphthyl surfactant is used to treat metallurgical powder, effectively reducing the surface viscosity of the metallurgical powder and the interfacial tension between it and the metal precipitate, resulting in more uniform mixing and better complexation between the two. Simultaneously, the benzopyrene structure in the naphthyl surfactant is similar to the polycyclic aromatic hydrocarbon structure in the catalytic oil slurry, which effectively improves the compatibility between the catalyst and the raw material, thus enhancing the conversion rate. The synergistic effect of the catalyst modified by the naphthyl surfactant and the catalytic oil slurry further improves the catalytic effect of waste edible oil.

[0133] 4. By using the catalyst and slurry bed hydrogenation process provided in the embodiments of the present invention to treat waste edible oils and catalytic slurry, these low-value-added petrochemical byproducts that seriously affect human health can be transformed into feedstock for fixed bed hydrogenation units and ultimately into clean fuel oil products, achieving the goal of treating waste with waste, significantly improving the economic efficiency of both, and conforming to the development trend of carbon neutrality.

[0134] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0135] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. A method for treating waste cooking oil, characterized in that, include: A hydrogenation catalyst is provided, the hydrogenation catalyst comprising a support and an active metal oxide coated on the surface of the support; The hydrogenation catalyst is mixed with catalytic slurry and waste edible oil to form a slurry hydrogenation bed. The mass ratio of waste edible oil to catalytic slurry in the slurry hydrogenation bed is 1:1 to 1:

9. The slurry hydrogenation bed is subjected to a hydrogenation reaction in a reducing atmosphere containing hydrogen. During the heating process before the hydrogenation reaction, the heating rate is less than 50°C / h within the temperature range of 200-250°C. The hydrogenation catalyst is prepared by the following method: 1) The carrier is treated with a solution of a naphthyl surfactant to obtain a modified carrier; 2) React the active metal salt with ammonia water to generate active metal crystals; 3) The modified support is mixed with the active metal crystal and reacted to obtain an active support mixture; 4) The active support mixture is calcined and pulverized to obtain the hydrogenation catalyst.

2. The processing method according to claim 1, characterized in that, The carrier comprises metallurgical powder, and the active metal oxide comprises molybdenum oxide.

3. The processing method according to claim 2, characterized in that, The active metal oxide includes molybdenum trioxide.

4. The processing method according to claim 3, characterized in that, The hydrogenation catalyst has an active metal oxide mass fraction of 1-3% and a particle size of 80-100 μm.

5. The processing method according to claim 1, characterized in that, In step 1), the volume ratio of the carrier to the naphthyl surfactant solution is 1:1 to 1:

2.

6. The processing method according to claim 1, characterized in that, The processing time in step 1) is 30-150 min. Step 2) specifically includes: adding ammonia water dropwise to the aqueous solution of the active metal salt to carry out the reaction.

7. The processing method according to claim 6, characterized in that, The ammonia solution has a mass concentration of 5-10%, and the dropping rate is 1-5 ml / s per liter of aqueous solution of active metal salt.

8. The processing method according to claim 1, characterized in that, Step 3) specifically includes: adding the modified carrier to the mixture of active metal crystals, wherein the addition rate of the modified carrier is 1-5 g / s per liter of the mixture of active metal crystals, and the reaction time in step 3) is 0.5-1 h; in step 4), the calcination temperature is 260-300℃ and the time is 5-8 h.

9. The processing method according to claim 1, characterized in that, The slurry hydrogenation bed also includes sulfur. In the slurry hydrogenation bed, the hydrogenation catalyst accounts for 0.1-0.5% of the total mass of the catalytic slurry and waste edible oil, and the hydrogenation catalyst accounts for 70-100% of the total mass of the sulfur.

10. The processing method according to claim 1, characterized in that, The hydrogenation reaction is carried out at a temperature of 400-450℃, a pressure of 10-25MPa, and a time of 30-60min.

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