Hydrogenation process for producing paraffin

Abstract

The invention provides a hydrogenation process for producing paraffin, which comprises the following steps: first-stage hydrogenation: mixing a degassed crude paraffin raw material with hydrogen, carrying out first-stage hydrogenation reaction under the action of a protective agent and a first hydrogenation catalyst, and separating and deodorizing to obtain a semi-refined paraffin product or a full-refined paraffin product; second-stage hydrogenation: mixing the fully refined paraffin product with hydrogen, carrying out second-stage hydrogenation reaction under the action of a second hydrogenation catalyst, and separating to obtain a food-grade paraffin product; the second hydrogenation catalyst is obtained by mixing a biomass raw material and a magnesium-containing organic salt, performing carbonization treatment, and performing co-precipitation on the prepared carbon material, an active component precursor and a precipitant. According to the hydrogenation process for producing the paraffin, a semi-refined paraffin product or a full-refined paraffin product and food-grade paraffin can be obtained at the same time, and the hydrogenation process is suitable for processing a carclazyte-free reverse-sequence inferior paraffin raw material, so that the quality and yield of the paraffin product are improved, the variety of the product is expanded, and the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of petroleum refining, specifically relating to a hydrogenation process for producing paraffin wax. Background Technology

[0002] Paraffin wax is mainly classified into food-grade paraffin wax and industrial paraffin wax according to its refining degree. Food-grade paraffin wax is further divided into food-grade paraffin wax and food packaging paraffin wax. Food-grade paraffin wax is suitable for use in food chewing gum, pharmaceutical components, demolding, tableting, polishing, and other applications that come into direct contact with food and pharmaceuticals. Currently, my country's food-grade paraffin wax market is still in its early stages, with only small and medium-sized chemical enterprises producing it domestically, resulting in low output that cannot meet market demand. With the continuous deepening of technological progress in the petrochemical industry and the continuous development of the economy and society, the application and development of paraffin wax are becoming more widely used in high-end fields such as food, cosmetics, and pharmaceuticals.

[0003] Existing paraffin hydrogenation industrial plants mostly employ medium-pressure single reactors or single-stage series processes. The catalyst carriers used are primarily alumina or modified alumina, with active components such as Ni-W, Mo-Ni, and W-Mo-Ni. These are used to remove non-ideal components such as sulfur, nitrogen, oxygen, olefins, and polycyclic aromatic hydrocarbons from paraffin feedstock. The main products are semi-refined or fully refined paraffin wax. However, in actual production, paraffin products still contain trace amounts of polycyclic aromatic hydrocarbons that are difficult to remove. This results in the product's odor failing to meet food-grade paraffin wax standards, making it unsuitable for use in food, cosmetics, and health and beauty industries, thus limiting its application areas and market competitiveness.

[0004] Chinese patent document CN100594233C discloses a two-stage hydrogenation method for producing white microcrystalline wax. This method employs a two-stage medium-pressure hydrogenation technology, using an anti-sulfur catalyst in the first stage and a reducing nickel catalyst in the second stage. Under certain process conditions, the resulting polycyclic aromatic hydrocarbons meet the requirements for food-grade waxes. However, the effluent from the first reactor undergoes only simple gas-liquid separation before entering the second reactor. Although hydrogen gas free of hydrogen sulfide is used as the hydrogen source, a small amount of hydrogen sulfide still dissolves in the liquid phase, poisoning the reducing catalyst in the second reactor and affecting the long-term operation of the equipment.

[0005] Chinese patent document CN101619241A discloses a method for hydrorefining paraffin wax. Paraffin wax raw material is mixed with hydrogen and then fed into a first reactor, where it contacts a sulfide-type non-precious metal hydrorefining catalyst for a hydrogenation reaction. The effluent from the first reactor is separated into gas and liquid phases, and the resulting liquid phase is mixed with hydrogen and fed into a second reactor. The second reactor uses a reducing catalyst, and its effluent, after gas-liquid separation, yields a food-grade paraffin wax product. However, only one high-pressure thermal separator is installed between the first and second reactors. When processing paraffin wax raw materials with a sulfur content >80 μg / g, the dissolved hydrogen sulfide in the effluent from the first reactor will affect the performance of the reducing catalyst in the second reactor. Furthermore, this process lacks a product stripping and deodorization step, making it difficult to meet the food-grade paraffin wax requirements for paraffin wax raw materials currently lacking clay refining.

[0006] Chinese patent document CN111978990A discloses a method for refining microcrystalline wax, specifically a refining scheme for microcrystalline wax produced from intermediate-base crude oil. The method comprises three reaction zones. First, crude microcrystalline wax is mixed with hydrogen and, in the presence of a hydrocracking catalyst, passes through a first hydrogenation reaction zone. The resulting effluent, without separation, passes through a second hydrogenation reaction zone in the presence of a paraffin hydrorefining catalyst. The effluent from the second hydrogenation reaction then passes through a third hydrogenation reaction zone in the presence of a paraffin hydrorefining catalyst. The resulting effluent is then separated to obtain a food-grade microcrystalline wax product. While this method yields food-grade microcrystalline wax, the process is lengthy, and the use of a hydrocracking catalyst reduces the wax product yield.

[0007] Chinese patent document CN102311804A discloses a method for hydrorefining paraffin wax, which uses a reducing catalyst to complete the desulfurization, nitrogen, oxygen, and aromatic saturation reactions. However, due to the current shutdown of clay refining units by various production enterprises, the quality of paraffin wax raw materials has deteriorated significantly. A single-stage medium-pressure hydrogenation process using a reducing catalyst alone is insufficient for the stable production of food-grade paraffin wax. Furthermore, the high content of impurities such as sulfur, nitrogen, and oxygen in the raw materials will lead to sulfur poisoning of the reducing catalyst, affecting the long-term stable operation of the equipment.

[0008] Chinese patent document CN111978989A discloses a method for the stable production of fully refined paraffin wax. Using crude paraffin wax prepared from a mixture of paraffin-based and intermediate-based crude oil as raw material, the method proceeds through a fixed-bed hydrogenation reactor in the presence of hydrogen and a paraffin wax hydrogenation refining catalyst to obtain fully refined paraffin wax. This method is particularly suitable for the hydrogenation process of producing fully refined paraffin wax from crude paraffin wax obtained by blending less than 30 wt% intermediate-based crude oil. However, it cannot produce food-grade paraffin wax. Summary of the Invention

[0009] In view of this, the present invention provides a hydrogenation process for producing paraffin wax, which can simultaneously obtain semi-refined or fully refined paraffin wax products and food-grade paraffin wax that meets GB 1886.26-2016 standards. It is also applicable to processing inferior paraffin wax raw materials without bleaching clay to produce food-grade paraffin wax that meets GB 1886.26-2016 standards, thereby improving the quality and yield of paraffin wax products, expanding product variety, and reducing production costs.

[0010] To achieve the above objectives, the present invention provides a hydrogenation process for producing paraffin wax, comprising the following steps:

[0011] First stage of hydrogenation: After the degassed crude paraffin raw material is mixed with hydrogen, a first stage of hydrogenation reaction is carried out under the action of a protective agent and a first hydrogenation catalyst. After separation and deodorization, semi-refined paraffin products or fully refined paraffin products are obtained.

[0012] Two-stage hydrogenation: The fully refined paraffin product is mixed with hydrogen and then subjected to a two-stage hydrogenation reaction under the action of a second hydrogenation catalyst. After separation, food-grade paraffin product is obtained.

[0013] The preparation method of the second hydrogenation catalyst includes the following steps:

[0014] Step 1: Mix biomass raw materials and magnesium-containing organic salts, and carbonize them to obtain carbon materials;

[0015] Step 2: Co-precipitate the carbon material, the active component precursor, and the precipitant to obtain the second hydrogenation catalyst.

[0016] The second hydrogenation catalyst provided by this invention has a non-precious metal active component, such as nickel, and is a reduced-state non-precious metal carbon-based catalyst. It possesses dual functions of hydrogenation and adsorption, capable of removing residual monocyclic aromatic hydrocarbons and other odor-causing impurities from paraffin products, thereby producing food-grade paraffin. This improves product quality for paraffin manufacturers, expands product range, and meets diverse market demands. By employing a co-precipitation method, a high-nickel-content active component catalyst is synthesized, avoiding the problem of uneven dispersion of the active component on the carrier surface due to multiple impregnations. Carbon materials possess good chemical stability, excellent adsorption performance, high specific surface area, and a regular pore structure, enabling the effective removal of trace amounts of monocyclic aromatic hydrocarbons from paraffin products, thus producing food-grade paraffin that meets the requirements of GB 1886.26-2016.

[0017] In one optional embodiment, the magnesium-containing organic salt is magnesium acetate and / or magnesium gluconate; the biomass feedstock is heavy bio-oil with a polycyclic aromatic hydrocarbon content of more than 70 wt%; and the mass ratio of the biomass feedstock to the magnesium-containing organic salt is (1-3):1.

[0018] In one optional embodiment, the mixing temperature of the biomass raw material and the magnesium-containing organic salt is 100-150°C, and the mixing time is 1-5 hours.

[0019] In one optional embodiment, the carbonization treatment is carried out at a temperature of 600–900°C for 1–5 hours, and the carbonization treatment is carried out in an inert atmosphere selected from at least one of nitrogen, helium, and argon. After the carbonization treatment, the process further includes acid washing and drying to obtain carbon material.

[0020] In one optional embodiment, the acid used for pickling is at least one of dilute nitric acid, dilute hydrochloric acid, and dilute sulfuric acid, with an acid concentration of 0.5–1.5 mol / L, and the pickling is performed until the magnesium content of the carbon material is 0.5 wt%–3 wt%; the drying temperature is 80–150°C, and the drying time is 2–8 h.

[0021] In one optional embodiment, in step 2, the carbon material is first sieved to obtain 150-300 mesh particles, and then co-precipitated with the active component precursor and the precipitant; the active component precursor is a nickel-soluble salt, and the precipitant is a carbonate.

[0022] In one optional embodiment, in step 2, the carbon material is mixed with water to form a slurry, the active component precursor is mixed with water to form an active component precursor solution, and the precipitant is mixed with water to form a precipitant solution. Then, the active component precursor solution, the precipitant solution, and the slurry are mixed for co-precipitation.

[0023] In one optional embodiment, in step 2, the concentration of the active component precursor solution, calculated as metal oxide, is 0.5–1.5 mol / L; the concentration of the precipitant solution is 0.5–1.5 mol / L.

[0024] In an optional embodiment, in step 2, the active component precursor solution and the precipitant solution are added to the slurry for mixing, controlling the pH value between 7 and 9, the temperature between 30 and 50°C, and precipitation for 0.5 to 2 hours. The co-precipitation process further includes post-treatment: the mixture is subjected to solid-liquid separation, and the resulting precipitate is dried, calcined, and shaped to obtain the second hydrogenation catalyst. The solid-liquid separation method is not particularly limited; for example, filtration is used. When the conductivity of the filtrate is ≤50 μS / cm, the filter cake is removed, dried at 100–140°C for 1–5 hours, then calcined at 200–400°C for 3–8 hours, and finally shaped to obtain the second hydrogenation catalyst. Shaping can be done by tableting or extrusion. The catalyst needs to be reduced in a hydrogen atmosphere before use; the reduction scheme is known in the art.

[0025] In one optional embodiment, the active component, calculated as a metal oxide, is present in the second hydrogenation catalyst at a content of 30 wt% to 50 wt%, and the specific surface area of ​​the second hydrogenation catalyst is 300 to 550 m². 2 / g, pore volume is 0.3~0.8cm³ 3 / g, with an average pore size of 8–15 nm.

[0026] In one optional embodiment, the conditions for the hydrogenation reaction include: a hydrogen partial pressure of 4–10 MPa and a volume hourly space velocity of 0.2–2.0 h⁻¹. -1 The hydrogen-to-wax volume ratio is 100–500:1; preferably, the conditions for the first-stage hydrogenation reaction include: hydrogen partial pressure 6–8 MPa and volume hourly space velocity 0.5–1.0 h⁻¹. -1 The volume ratio of hydrogen wax is 150 to 300:1.

[0027] In one optional embodiment, the conditions for the two-stage hydrogenation reaction include: a hydrogen partial pressure of 4–10 MPa and a volume hourly space velocity of 0.5–4.0 h⁻¹. -1 The hydrogen-to-wax volume ratio is 50–300:1; preferably, the conditions for the first-stage hydrogenation reaction include: hydrogen partial pressure 6–8 MPa and volume hourly space velocity 1.0–2.0 h⁻¹. -1 The volume ratio of hydrogen wax is 100-200:1.

[0028] In one optional embodiment, in the hydrogenation step, the degassed crude paraffin raw material is mixed with hydrogen and preheated to 220-310°C (preferably 240-280°C) to carry out a hydrogenation reaction.

[0029] In one optional embodiment, in the two-stage hydrogenation step, the fully refined paraffin product is mixed with hydrogen and preheated to 200-280°C (preferably 220-260°C) before undergoing a two-stage hydrogenation reaction.

[0030] In one optional embodiment, the volume ratio of the protective agent to the first hydrogenation catalyst is 0.05 to 0.25, preferably 0.1 to 0.2; the protective agent is selected from inert protective agents and active protective agents, the inert protective agent is a shaped α-alumina protective agent, and the active protective agent is metal-supported γ-alumina, wherein the metal is calculated as an oxide, and the weight content of the metal in the active protective agent is 1% to 30% (preferably 3.0% to 15.0%), wherein the metal is selected from at least one of Co, Mo, W, and Ni.

[0031] In one optional embodiment, the hydrogenation reactor is sequentially filled with a protective agent and a first hydrogenation catalyst in the direction of material flow. Preferably, the volume ratio of the inert protective agent to the active protective agent is 0.1 to 0.3, and the bed porosity of the inert protective agent is 1.2 to 2.0 times that of the bed porosity of the active protective agent.

[0032] In one optional embodiment, the first hydrogenation catalyst comprises a support and an active component. The active component includes at least one of Co, Mo, W, and Ni, and the active component, calculated as an oxide, has a weight content of 10% to 50% (preferably 25% to 35%) in the first hydrogenation catalyst. The support comprises alumina and / or amorphous silica-alumina. The first hydrogenation catalyst can be a commercially available catalyst, such as the PHF-P series protective agents and catalysts SD-1, SD-2, and PHF-401 developed by the Petrochemical Research Institute of China National Petroleum Corporation. The protective agent and the active component of the catalyst are typically in an oxidized state and require sulfidation treatment before use; conventional sulfidation methods are acceptable.

[0033] In one optional embodiment, specifically, the hydrogenation process for producing paraffin provided by the present invention includes the following steps:

[0034] First-stage hydrogenation: After the degassed crude paraffin raw material is mixed with hydrogen, it is preheated in a first-stage heating furnace, and then enters a first-stage hydrogenation reactor containing a protective agent and a first-stage hydrogenation catalyst for a first-stage hydrogenation reaction (to remove impurities such as sulfur, nitrogen, oxygen and metals, while saturating some polycyclic aromatic hydrocarbons). After removing hydrogen sulfide, ammonia and water through high and low gas-liquid separation, it enters a stripping drying tower for deodorization treatment. The bottom effluent of the stripping drying tower is the semi-refined paraffin product or the fully refined paraffin product.

[0035] Two-stage hydrogenation: The fully refined paraffin product is mixed with hydrogen and preheated in a two-stage heating furnace. Then it enters a two-stage hydrogenation reactor containing a second hydrogenation catalyst to carry out a two-stage hydrogenation reaction (hydrogenation saturates the small amount of residual aromatics in the fully refined paraffin product). After gas-liquid separation, a food-grade paraffin product that meets the requirements of GB 1886.26-2016 is obtained.

[0036] The preparation method of the second hydrogenation catalyst is as described above.

[0037] The beneficial effects of this invention are:

[0038] The hydrogenation process for producing paraffin wax provided by this invention employs a two-stage hydrogenation process combined with a specific second-stage hydrogenation catalyst. This process can produce semi-refined paraffin wax, fully refined paraffin wax, and food-grade paraffin wax (food packaging wax and food additives), improving the quality of paraffin wax products, expanding product variety, and reducing production costs. Furthermore, the entire process has a long and stable operating cycle. Specifically, the first-stage hydrogenation reaction utilizes a protective agent and a graded first catalyst packing method to process raw materials such as inferior paraffin wax refined without clay. The catalyst bed is controlled along the material direction, with adjustments made to the shape, size, and activity of the protective agent and catalyst, allowing impurities in the raw materials to be removed in a step-by-step, orderly manner, delaying the increase in reactor pressure drop, and thus extending the operating cycle of the unit. The second-stage hydrogenation reaction employs a second hydrogenation catalyst with dual functions of hydrogenation and adsorption, which can better remove residual monocyclic aromatic hydrocarbons from the paraffin wax product, ensuring that the hydrogenated product meets the requirements for food-grade paraffin wax. For example, when the oil content of the paraffin raw material is >0.5wt%, the first stage of hydrogenation in this scheme can be selected to produce semi-refined paraffin that meets GB / T 254-2022 or fully refined paraffin that meets GB / T446-2023, depending on the demand; when the oil content of the paraffin raw material is ≤0.5wt%, a two-stage hydrogenation process can be used to produce paraffin products that meet GB1886.26-2016 food additive standards.

[0039] The second hydrogenation catalyst is prepared by first carbonizing biomass feedstock and magnesium-containing organic salts to obtain carbon material, and then co-precipitating this carbon material with an active component precursor and a precipitant. The magnesium content reduces the acidity of the catalyst surface, thus preventing the cracking reaction of paraffin even during paraffin hydrogenation at higher reaction temperatures. In addition, using magnesium-containing organic salts as template agents, the resulting catalyst has an average pore size of 8–15 nm, making it suitable for paraffin hydrogenation refining. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a hydrogenation process for producing paraffin wax, provided by the present invention.

[0041] Among them, 1: raw material pump, 2: raw material degassing tower, 3: first stage heating furnace, 4: first stage hydrogenation reactor, 5: first stage high pressure separator, 6: first stage low pressure separator, 7: stripping drying tower, 8: second stage raw material pump, 9: second stage heating furnace, 10: second stage hydrogenation reactor, 11: second stage high pressure separator, 12: second stage low pressure separator. Detailed Implementation

[0042] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution of the present invention and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0043] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0044] The carbon source used in the embodiments of this invention is heavy oil obtained by pyrolysis of industrial wood raw materials, with a polycyclic aromatic hydrocarbon content of 75.5 wt%.

[0045] The crude paraffin raw materials used in the embodiments of this invention are No. 56, No. 58 and No. 64 crude paraffin refined without bleaching clay by Daqing Refining & Chemical Branch of China National Petroleum Corporation. Their properties are shown in Table 1.

[0046] The content of polycyclic aromatic hydrocarbons in crude paraffin raw materials and hydrogenated products is expressed by the simplified method of ultraviolet absorbance.

[0047] For ease of comparison, the protective agents used in the embodiments of this invention are PHF-P-01, PHF-P-02, PHF-P-03, and PHF-P-04 developed by the Petrochemical Research Institute of China National Petroleum Corporation; the first hydrogenation catalyst is SD-2 developed by the Petrochemical Research Institute of China National Petroleum Corporation. The loading of the protective agents and catalysts is shown in Table 2.

[0048] Table 1 Properties of crude paraffin raw materials

[0049]

[0050]

[0051] Table 2. Gradation and Packing of Protective Agents and Catalysts

[0052]

[0053] Unless otherwise specified, the experimental materials used in the following examples can be purchased from the market.

[0054] Example 1

[0055] Preparation of the second hydrogenation catalyst

[0056] (1) Take 32g of magnesium acetate and add it to 64g of heavy oil from wood pyrolysis. Stir at 120℃ for 2h to obtain mixture A. Then place the mixture in a muffle furnace, purge the air with nitrogen, and heat it to 850℃ at 40℃ / h under this inert atmosphere. Carbonize it at 850℃ for 3h to obtain 44.2g of carbon intermediate. Treat the carbon intermediate with 104mL of 1.0mol / L dilute hydrochloric acid for 30min. Take out the insoluble matter and dry it at 120℃ for 4h to obtain 35.8g of mesoporous carbon material B. Grind it through an 180-mesh sieve to obtain carbon powder. Take 30g of carbon powder and add it to a beaker containing 800mL of deionized water to make slurry C.

[0057] (2) Dissolve 80.8g of nickel nitrate hexahydrate in 240mL of deionized water to obtain a NiO solution D with a concentration of 1.0mol / L. Dissolve 29.7g of anhydrous sodium carbonate in 250mL of deionized water to obtain a Na2CO3 solution E with a concentration of 1.1mol / L. Then add D and E in parallel to slurry C, adjust the pH value between 7.8 and 8.2, and age at 45℃ for 1.5h. Wash the insoluble matter with deionized water and filter five times. At this time, the conductivity of the filtrate is 35.5μs / cm. Take out the filter cake F, dry it at 120℃ for 2h, calcine it at 380℃ for 3.5h, and then press it into tablets to form catalyst G1. The properties are shown in Table 3.

[0058] Hydrogenation process for producing paraffin

[0059] use Figure 1 The flowchart shown illustrates that No. 56 crude paraffin wax is pressurized by raw material pump 1 and then sent to raw material degassing tower 2 for degassing. It is then heated to 240°C together with hydrogen in a first-stage heater 3, and subsequently enters a first-stage hydrogenation reactor 4 at a hydrogen partial pressure of 6.0 MPa, a hydrogen-to-paraffin ratio of 150:1, and a volume hourly space velocity of 1.0 h⁻¹. -1 Under certain conditions, impurities such as sulfur, nitrogen, oxygen, and polycyclic aromatic hydrocarbons are removed. The product then undergoes gas-liquid separation via a high-pressure separator 5 and a low-pressure separator 6 to separate hydrogen-rich and hydrogen-poor components. The liquid enters a stripping dryer 7 where residual hydrogen sulfide and other gases are removed under superheated steam conditions, yielding fully refined paraffin wax (if necessary, only one stage of hydrogenation can be selected to produce semi-refined paraffin wax). The wax is then pressurized by a second-stage feed pump 8 and heated to 220°C in a second-stage heater 9 before entering a second-stage hydrogenation reactor 10 (using the aforementioned catalyst G1). The reactor operates at a hydrogen partial pressure of 6.0 MPa, a hydrogen-to-wax ratio of 100:1, and a volumetric hourly space velocity (VHSV) of 2.0 h⁻¹. -1 Impurities such as saturated monocyclic aromatic hydrocarbons are removed under certain conditions, and then hydrogen-rich and hydrogen-poor substances are separated by a two-stage high-pressure separator 11 and a two-stage low-pressure separator 12 to obtain food-grade paraffin. The properties of the hydrogenated products are shown in Table 4.

[0060] Example 2

[0061] The preparation of the second hydrogenation catalyst was the same as in Example 1, except that the carbonization conditions were 700℃ for 4.5h and the filter cake F was calcined at 320℃ for 4.5h, with other conditions remaining unchanged, to prepare catalyst G2, the properties of which are shown in Table 3.

[0062] Hydrogenation process for producing paraffin

[0063] use Figure 1 The flowchart shown illustrates that No. 56 crude paraffin wax is pressurized by raw material pump 1 and sent to raw material degassing tower 2 for degassing. It is then heated to 240°C in a primary heater 3 along with hydrogen, and then enters a primary hydrogenation reactor 4 at a hydrogen partial pressure of 7.0 MPa, a hydrogen-to-paraffin ratio of 300:1, and a volume hourly space velocity of 1.0 h⁻¹. -1Under certain conditions, impurities such as sulfur, nitrogen, oxygen, and polycyclic aromatic hydrocarbons are removed. The product then undergoes gas-liquid separation via a high-pressure separator 5 and a low-pressure separator 6 to separate hydrogen-rich and hydrogen-poor components. The liquid enters a stripping dryer 7 where residual hydrogen sulfide and other gases are removed under superheated steam conditions, yielding fully refined paraffin wax. This wax is then pressurized by a second-stage feed pump 8 and heated to 220°C in a second-stage heater 9 before entering a second-stage hydrogenation reactor 10 (using the aforementioned catalyst G2). The process is carried out at a hydrogen partial pressure of 7.0 MPa, a hydrogen-to-wax ratio of 100:1, and a volumetric hourly space velocity (VHSV) of 2.0 h⁻¹. -1 Impurities such as saturated monocyclic aromatic hydrocarbons are removed under certain conditions, and then hydrogen-rich and hydrogen-poor substances are separated by a two-stage high-pressure separator 11 and a two-stage low-pressure separator 12 to obtain food-grade paraffin. The properties of the hydrogenated products are shown in Table 4.

[0064] Example 3

[0065] The preparation of the second hydrogenation catalyst was the same as in Example 1, except that 80.8 g of nickel nitrate hexahydrate was dissolved in 155 mL of deionized water to obtain a NiO solution D with a concentration of 1.5 mol / L, and 29.7 g of anhydrous sodium carbonate was dissolved in 560 mL of deionized water to obtain a Na2CO3 solution E with a concentration of 0.5 mol / L. The catalysts were aged at 45 °C for 1.0 h under the same conditions to prepare catalyst G3. The properties are shown in Table 3.

[0066] Hydrogenation process for producing paraffin

[0067] use Figure 1 The flowchart shown illustrates that crude paraffin wax (No. 58) is pressurized by raw material pump 1 and then sent to raw material degassing tower 2 for degassing. It is then heated to 255°C together with hydrogen in a first-stage heater 3, and subsequently enters a first-stage hydrogenation reactor 4 at a hydrogen partial pressure of 7.0 MPa, a hydrogen-to-paraffin ratio of 220:1, and a volume hourly space velocity (VHSV) of 0.8 h⁻¹. -1 Under certain conditions, impurities such as sulfur, nitrogen, oxygen, and polycyclic aromatic hydrocarbons are removed. The product then undergoes gas-liquid separation via a high-pressure separator 5 and a low-pressure separator 6 to separate hydrogen-rich and hydrogen-poor components. The liquid enters a stripping dryer 7 where residual hydrogen sulfide and other gases are removed under superheated steam conditions, yielding fully refined paraffin wax. This wax is then pressurized by a second-stage feed pump 8 and heated to 220°C in a second-stage heater 9 before entering a second-stage hydrogenation reactor 10 (using the aforementioned catalyst G3). The process is carried out at a hydrogen partial pressure of 7.0 MPa, a hydrogen-to-wax ratio of 150:1, and a volumetric hourly space velocity (VHSV) of 1.6 h⁻¹. -1 Impurities such as saturated monocyclic aromatic hydrocarbons are removed under certain conditions, and then hydrogen-rich and hydrogen-poor substances are separated by a two-stage high-pressure separator 11 and a two-stage low-pressure separator 12 to obtain food-grade paraffin. The properties of the hydrogenated products are shown in Table 4.

[0068] Example 4

[0069] Preparation of the second hydrogenation catalyst

[0070] (1) Take 49g of magnesium gluconate and add it to 74g of heavy oil from wood pyrolysis. Stir at 120℃ for 2h to obtain mixture A. Then place the mixture in a muffle furnace, purge the air with helium, and heat it to 800℃ at 40℃ / h under this inert atmosphere. Carbonize it at 800℃ for 3.5h to obtain 49.7g of carbon intermediate. Treat the carbon intermediate with 200mL of 1.0mol / L dilute hydrochloric acid for 30min. Take out the insoluble matter and dry it at 110℃ for 5h to obtain 41.5g of mesoporous carbon material B. Grind it through a 180-mesh sieve to obtain carbon powder. Take 30g of carbon powder and add it to a beaker containing 800mL of deionized water to make slurry C.

[0071] (2) Dissolve 43.5g of nickel sulfate in 280mL of deionized water to obtain a NiO solution D with a concentration of 1.0mol / L. Then dissolve 29.8g of anhydrous sodium carbonate in 310mL of deionized water to obtain a Na2CO3 solution E with a concentration of 0.9mol / L. Then add D and E in parallel to slurry C, adjust the pH value between 7.8 and 8.2, and age at 40℃ for 1.5h. Wash the insoluble matter with deionized water five times. At this time, the conductivity of the filtrate is 38.5μs / cm. Take out the filter cake F, dry it at 120℃ for 2h, calcine it at 380℃ for 3.5h, and then press it into tablets to form catalyst G4. The properties are shown in Table 3.

[0072] Hydrogenation process for producing paraffin

[0073] use Figure 1 The flowchart shown illustrates that crude paraffin wax (No. 58) is pressurized by raw material pump 1 and then sent to raw material degassing tower 2 for degassing. It is then heated to 255°C together with hydrogen in a first-stage heater 3, and subsequently enters a first-stage hydrogenation reactor 4 at a hydrogen partial pressure of 7.0 MPa, a hydrogen-to-paraffin ratio of 220:1, and a volume hourly space velocity (VHSV) of 0.8 h⁻¹. -1 Under certain conditions, impurities such as sulfur, nitrogen, oxygen, and polycyclic aromatic hydrocarbons are removed. The product then undergoes gas-liquid separation via a high-pressure separator 5 and a low-pressure separator 6 to separate hydrogen-rich and hydrogen-poor components. The liquid enters a stripping dryer 7 where residual hydrogen sulfide and other gases are removed under superheated steam conditions, yielding fully refined paraffin wax. This wax is then pressurized by a second-stage feed pump 8 and heated to 230°C in a second-stage heater 9 before entering a second-stage hydrogenation reactor 10 (using the aforementioned catalyst G4). The process is carried out at a hydrogen partial pressure of 7.0 MPa, a hydrogen-to-wax ratio of 200:1, and a volumetric hourly space velocity (VHSV) of 1.6 h⁻¹. -1 Impurities such as saturated monocyclic aromatic hydrocarbons are removed under certain conditions, and then hydrogen-rich and hydrogen-poor substances are separated by a two-stage high-pressure separator 11 and a two-stage low-pressure separator 12 to obtain food-grade paraffin. The properties of the hydrogenated products are shown in Table 4.

[0074] Example 5

[0075] The preparation of the second hydrogenation catalyst was the same as in Example 4, except that the carbon intermediate was treated with 250 mL of 0.8 mol / L dilute sulfuric acid for 30 min, and the insoluble matter was removed and dried at 140 °C for 3 h to obtain 41.7 g of mesoporous carbon material B. Under the same conditions, catalyst G5 was prepared, and its properties are shown in Table 3.

[0076] Hydrogenation process for producing paraffin

[0077] use Figure 1 The flowchart shown illustrates that crude paraffin wax (No. 64) is pressurized by raw material pump 1 and then sent to raw material degassing tower 2 for degassing. It is then heated to 275°C together with hydrogen in a first-stage heater 3, and then enters stage 4 where the hydrogen partial pressure is 7.0 MPa, the hydrogen-to-paraffin ratio is 300:1, and the volume hourly space velocity (VHSV) is 0.5 h⁻¹. -1 Under certain conditions, impurities such as sulfur, nitrogen, oxygen, and polycyclic aromatic hydrocarbons are removed. The product then undergoes gas-liquid separation via a high-pressure separator 5 and a low-pressure separator 6 to separate hydrogen-rich and hydrogen-poor components. The liquid enters a stripping dryer 7 where residual hydrogen sulfide and other gases are removed under superheated steam conditions, yielding fully refined paraffin wax. This wax is then pressurized by a second-stage feed pump 8 and heated to 245°C in a second-stage heater 9 before entering a second-stage hydrogenation reactor 10 (using the aforementioned catalyst G5). The process is carried out at a hydrogen partial pressure of 7.0 MPa, a hydrogen-to-wax ratio of 150:1, and a volumetric hourly space velocity (VHSV) of 1.0 h⁻¹. -1 Impurities such as saturated monocyclic aromatic hydrocarbons are removed under certain conditions, and then hydrogen-rich and hydrogen-poor substances are separated by a two-stage high-pressure separator 11 and a two-stage low-pressure separator 12 to obtain food-grade paraffin. The properties of the hydrogenated products are shown in Table 4.

[0078] Example 6

[0079] The preparation of the second hydrogenation catalyst was the same as in Example 4, except that the carbon intermediate was treated with 150 mL of 1.4 mol / L dilute nitric acid for 30 min, while other conditions remained unchanged, to prepare catalyst G6, the properties of which are shown in Table 3.

[0080] Hydrogenation process for producing paraffin

[0081] use Figure 1 The flowchart shown illustrates that No. 64 crude paraffin wax is pressurized by raw material pump 1 and then sent to raw material degassing tower 2 for degassing. It is then heated to 275°C together with hydrogen in a first-stage heater 3, and subsequently enters a first-stage hydrogenation reactor 4 at a hydrogen partial pressure of 8.0 MPa, a hydrogen-to-paraffin ratio of 300:1, and a volume hourly space velocity of 0.5 h⁻¹. -1Under certain conditions, impurities such as sulfur, nitrogen, oxygen, and polycyclic aromatic hydrocarbons are removed. The product then undergoes gas-liquid separation via a high-pressure separator 5 and a low-pressure separator 6 to separate hydrogen-rich and hydrogen-poor components. The liquid enters a stripping dryer 7 where residual hydrogen sulfide and other gases are removed under superheated steam conditions, yielding fully refined paraffin wax. This wax is then pressurized by a second-stage feed pump 8 and heated to 255°C in a second-stage heater 9 before entering a second-stage hydrogenation reactor 10 (using the aforementioned catalyst G6). The process is carried out at a hydrogen partial pressure of 8.0 MPa, a hydrogen-to-wax ratio of 100:1, and a volumetric hourly space velocity (VHSV) of 1.0 h⁻¹. -1 Impurities such as saturated monocyclic aromatic hydrocarbons are removed under certain conditions, and then hydrogen-rich and hydrogen-poor substances are separated by a two-stage high-pressure separator 11 and a two-stage low-pressure separator 12 to obtain food-grade paraffin. The properties of the hydrogenated products are shown in Table 4.

[0082] Comparative Example 1

[0083] Preparation of the second hydrogenation catalyst

[0084] (1) Take 32g of magnesium acetate and add it to 64g of heavy oil from wood pyrolysis. Stir at 120℃ for 2h to obtain mixture A. Then place the mixture in a muffle furnace, purge the air with nitrogen, and heat it to 850℃ at 40℃ / h under this inert atmosphere. Carbonize it at 850℃ for 3h to obtain 44.2g of carbon intermediate. Treat the carbon intermediate with 104mL of 1.0mol / L dilute hydrochloric acid for 30min. Take out the insoluble matter and dry it at 120℃ for 4h to obtain 35.8g of mesoporous carbon material B. Grind it through a 180-mesh sieve to obtain 35g of carbon powder. Add 4g of 25wt% nitric acid, 1g of guar gum powder, 1g of citric acid and an appropriate amount of deionized water to it. Mix and extrude it into shape. Dry it at 120℃ for 4h under an inert atmosphere to obtain carbon carrier.

[0085] (2) Ammonium metatungstate, nickel nitrate and molybdenum trioxide were added to sulfuric acid solution and the pH was adjusted to 3.0 to obtain an impregnation solution containing tungsten, molybdenum and nickel (the content of tungsten oxide was 28.4 g / 100 mL, the content of molybdenum oxide was 7.3 g / 100 mL and the content of nickel oxide was 4.5 g / 100 mL). The impregnation solution containing tungsten, molybdenum and nickel was used to supersaturate the carbon support for 3 h at 110% of the saturated water absorption capacity of the carbon support. After impregnation, the carbon support was ultrasonically treated (ultrasonic frequency was 30 kHz) for 2 h, dried at 120 °C for 5 h under nitrogen atmosphere, and then calcined at 450 °C for 3 h under nitrogen atmosphere to prepare paraffin hydrogenation refining catalyst D1. The properties are shown in Table 3.

[0086] Hydrogenation process for producing paraffin

[0087] Similar to Example 6, except that catalyst D1 prepared in this comparative example is used instead of catalyst G6, and the properties of the hydrogenation products are shown in Table 4.

[0088] Comparative Example 2

[0089] Preparation of the second hydrogenation catalyst

[0090] (1) Mix 100g of industrial grade boehmite, 8.4g of 25wt% nitric acid, 3g of guar gum powder and 3g of citric acid and an appropriate amount of deionized water, extrude the mixture, dry it at 120℃ for 2h, and calcine it at 750℃ for 4h to prepare about 70g of alumina carrier with a water absorption rate of 85%.

[0091] (2) Take 50g of the above support and impregnate it three times with a supersaturated nickel nitrate solution (NiO content in the solution is 26.3g / 100mL) to obtain a catalyst precursor with high nickel content. Dry it at 120℃ for 4h and then calcine it at 480℃ in air for 3h to obtain paraffin hydrogenation supplemented refined aluminum-based catalyst D2. The properties are shown in Table 3.

[0092] Hydrogenation process for producing paraffin

[0093] Similar to Example 1, except that catalyst D2 prepared in this comparative example is used instead of catalyst G1, and the properties of the hydrogenation products are shown in Table 4.

[0094] Table 3. Physicochemical properties of catalysts

[0095]

[0096] As shown in Table 3, the high-nickel content catalyst prepared by impregnation method using alumina as a support in Comparative Example 2 has a specific surface area of ​​176 m². 2 / g, pore volume 0.30cm 3 / g, with an average pore size of 8.2 nm. Compared with Examples 1-6 and Comparative Example 1, the catalyst of Comparative Example 2 shows a significant difference in specific surface area, pore volume, and average pore size. This is mainly due to the high specific surface area and regular pore structure of the mesoporous carbon material obtained by the method of this invention.

[0097] Table 4 Product Properties

[0098]

[0099] As can be seen from Examples 1 to 6 above, the hydrogenation process of the present invention, combined with a two-stage hydrogenation catalyst, can produce paraffin products that meet the GB 1886.26-2016 food additive standard. In Comparative Example 1, the two-stage catalyst cannot achieve monocyclic aromatic saturation due to insufficient aromatic saturation performance. In Comparative Example 2, the two-stage catalyst uses a highly acidic alumina support, which leads to an increase in oil content in the hydrogenated product, and thus cannot achieve the production of food-grade paraffin.

[0100] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A hydrogenation process for producing paraffin wax, characterized in that, Includes the following steps: First stage of hydrogenation: After the degassed crude paraffin raw material is mixed with hydrogen, a first stage of hydrogenation reaction is carried out under the action of a protective agent and a first hydrogenation catalyst. After separation and deodorization, semi-refined paraffin products or fully refined paraffin products are obtained. Two-stage hydrogenation: The fully refined paraffin product is mixed with hydrogen and then subjected to a two-stage hydrogenation reaction under the action of a second hydrogenation catalyst. After separation, food-grade paraffin product is obtained. The preparation method of the second hydrogenation catalyst includes the following steps: Step 1: Mix biomass raw materials and magnesium-containing organic salts, and carbonize them to obtain carbon materials; Step 2: Co-precipitate the carbon material, the active component precursor, and the precipitant to obtain the second hydrogenation catalyst.

2. The hydrogenation process for producing paraffin according to claim 1, characterized in that, The magnesium-containing organic salt is magnesium acetate and / or magnesium gluconate; The biomass feedstock is a heavy bio-oil with a polycyclic aromatic hydrocarbon content of more than 70 wt%. The mass ratio of the biomass raw material to the magnesium-containing organic salt is (1-3):

1.

3. The hydrogenation process for producing paraffin according to claim 1, characterized in that, The mixing temperature of the biomass raw material and the magnesium-containing organic salt is 100-150°C, and the mixing time is 1-5 hours. The carbonization process is carried out at a temperature of 600–900°C for 1–5 hours.

4. The hydrogenation process for producing paraffin according to claim 1, characterized in that, In step 2, the carbon material is first sieved to obtain 150-300 mesh particles, and then co-precipitated with the active component precursor and the precipitant; the active component precursor includes a nickel-soluble salt, and the precipitant includes a carbonate.

5. The hydrogenation process for producing paraffin according to claim 1, characterized in that, During the co-precipitation process, the pH value is controlled between 7 and 9, the temperature is between 30 and 50°C, and the precipitation time is 0.5 to 2 hours. The co-precipitation process also includes post-treatment: the mixture is subjected to solid-liquid separation, and the resulting precipitate is dried, calcined, and shaped to obtain the second hydrogenation catalyst.

6. The hydrogenation process for producing paraffin according to claim 1, characterized in that, In the second hydrogenation catalyst, the content of the active component, calculated as metal oxide, is 30 wt% to 50 wt%; the specific surface area of ​​the second hydrogenation catalyst is 300 to 550 m². 2 / g, pore volume is 0.3~0.8cm³ 3 / g, with an average pore size of 8–15 nm.

7. The hydrogenation process for producing paraffin according to claim 1, characterized in that, The conditions for the hydrogenation reaction include: a hydrogen partial pressure of 4–10 MPa and a volume hourly space velocity of 0.2–2.0 h⁻¹. - 1. The volume ratio of hydrogen wax is 100–500:1; The conditions for the two-stage hydrogenation reaction include: a hydrogen partial pressure of 4–10 MPa and a volume hourly space velocity of 0.5–4.0 h⁻¹. -1 The volume ratio of hydrogen wax is 50 to 300:

1.

8. The hydrogenation process for producing paraffin according to claim 1, characterized in that, In the hydrogenation step, the degassed crude paraffin raw material is mixed with hydrogen, preheated to 220-310°C, and then subjected to a hydrogenation reaction. In the two-stage hydrogenation step, the fully refined paraffin product is mixed with hydrogen and preheated to 200-280°C before undergoing a two-stage hydrogenation reaction.

9. The hydrogenation process for producing paraffin according to claim 1, characterized in that, The volume ratio of the protective agent to the first hydrogenation catalyst is 0.05 to 0.25; the protective agent is selected from inert protective agents and / or active protective agents, the inert protective agent is a shaped α-alumina protective agent, the active protective agent is γ-alumina loaded with metal, the metal is calculated as oxide, the metal content in the active protective agent is 1% to 30% by weight, and the metal is selected from at least one of Co, Mo, W, and Ni.

10. The hydrogenation process for producing paraffin according to claim 1, characterized in that, The first hydrogenation catalyst includes a support and an active component, wherein the active component includes at least one of Co, Mo, W, and Ni, and the support includes alumina and / or amorphous silica-alumina; preferably, the active component, calculated as oxide, has a weight content of 10% to 50% in the first hydrogenation catalyst.

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