Hydrogenation system and hydrogenation method

Abstract

The application discloses a hydrogenation system and a hydrogenation method. The hydrogenation method comprises the following steps: firstly, reaction raw materials and hydrogen enter a gas phase container to become in a gas phase state, and the gas phase container is filled with inert fillers and / or inner members with fluid flow state distribution effect; secondly, the gas phase container effluent is subjected to pressure boosting treatment and enters a liquid phase hydrogenation reactor to perform a hydrogenation reaction in the liquid phase reactor; and finally, hydrogenation heavy components are discharged from the bottom of the liquid phase reactor to obtain hydrogenation products. The application combines the vaporization process and the liquefaction process of the reaction raw materials and the hydrogen, utilizes the phase change process to strengthen the uniform mixing and dissolution of the hydrogen and the raw materials, and further improves the reaction rate by combining the gas phase reaction and the liquid phase reaction.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation, and specifically relates to a hydrogenation system and a hydrogenation method. Background Technology

[0002] Liquid-phase hydrogenation technology solves the hydrogen recycling problem in hydrogenation processes. This technology dissolves hydrogen in the feedstock before it enters the reactor, so the feedstock is a liquid phase with dissolved hydrogen. A liquid-solid two-phase reaction occurs on the catalyst surface, reducing mass transfer resistance during hydrogen diffusion and improving reaction efficiency. Furthermore, since a large amount of hydrogen has already been consumed in the reaction, there is no excess hydrogen in the product exiting the reactor. Therefore, the product can be directly fractionated and sent to the fractionation tower, eliminating the need for hydrogen cooling and a circulating hydrogen compressor, significantly reducing energy consumption and construction investment. In recent years, it has achieved widespread industrial application and has expanded into areas such as jet fuel hydrogenation, reformate hydrogenation, and maleic anhydride hydrogenation. However, in the application of liquid-phase technology, to enhance hydrogen dissolution in the feedstock, a hydrogen mixing device is required. Forced back-mixing promotes hydrogen dissolution and typically requires pressure levels higher than the reaction requirements, leading to increased energy consumption. Currently, membrane-based hydrogen mixing facilities are generally expensive to purchase, increasing the overall construction investment for the hydrogenation process.

[0003] CN105038843A discloses a diesel vapor-phase hydrodesulfurization process, which uses a high vaporization rate, low pressure, and high hydrogen-to-oil ratio method to put the feedstock in a gas-phase reaction state, reduce the pressure of the reaction system, and increase the desulfurization reaction rate. However, due to the low pressure, the aromatic saturation effect of this method is poor, and the desulfurization depth cannot meet the latest China VI diesel quality standard.

[0004] CN111871337A discloses a micro-interface reaction system and method for diesel hydrotreating. By setting multiple micro-interface generators between the beds of the hydrotreating reactor, hydrogen is broken into microbubbles, enhancing the dispersion of hydrogen in the feedstock. However, micro-interface equipment is generally expensive, which is not conducive to further quality and efficiency improvements in refineries.

[0005] In the production of chemical raw materials, hydrogenation for impurity removal and refining is often involved, such as the hydrogenation of maleic anhydride to produce succinic anhydride, and the production of refined terephthalic acid from crude terephthalic acid. These technologies generally use the hydrogenation method. Since the raw materials are in a crystalline state at room temperature, liquid-phase hydrogenation is used, which involves the problem of uniform mixing of hydrogen. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a hydrogenation system and method. This invention combines the vaporization and liquefaction processes of the reactants and hydrogen, utilizing a phase change process to enhance the uniform mixing and dissolution of hydrogen with the reactants. Simultaneously, by combining gas-phase and liquid-phase reactions, the reaction rate is further increased.

[0007] The first aspect of the present invention provides a hydrogenation method comprising the following steps: the reaction raw materials and hydrogen gas first enter a gas phase container and become gas phase, the gas phase container being filled with inert packing material and / or internal components having a fluid flow distribution function; the effluent from the gas phase container is pressurized and enters a liquid phase hydrogenation reactor, where a hydrogenation reaction is carried out, and the resulting hydrogenated heavy components are discharged from the bottom of the liquid phase reactor, ultimately yielding a hydrogenated product.

[0008] Furthermore, the reaction raw materials can be conventional raw materials that require hydrogenation treatment, preferably at least one of maleic anhydride, crude terephthalic acid, etc., and the anhydride is preferably maleic anhydride.

[0009] Furthermore, when the reactant is maleic anhydride, the target product is succinic anhydride. When the reactant is crude terephthalic acid, the target product is purified terephthalic acid. The crude terephthalic acid contains impurities including one or more of p-methylbenzoic acid and p-carboxybenzaldehyde. The final purified terephthalic acid contains p-methylbenzoic acid <150 ppm and p-carboxybenzaldehyde <25 ppm, by mass.

[0010] Furthermore, when using maleic anhydride as a reaction raw material, γ-butyrolactone is generally used as a solvent, and a solution with a mass concentration of 10% to 20% is prepared based on the mass of maleic anhydride for feeding.

[0011] Furthermore, when crude terephthalic acid is used as the reaction raw material, demineralized water is generally used as the solvent, and a solution with a mass concentration of 20% to 35% is prepared based on the mass of crude terephthalic acid for feeding.

[0012] Furthermore, the purchased component can be a jet-type distributor or a gas phase distribution tray, etc. The inert packing can be one or more of ceramic balls, Raschig rings, etc.

[0013] Furthermore, the pressurization can be achieved using a conventional commercial compressor, such as a reciprocating or centrifugal compressor.

[0014] Furthermore, the operating conditions of the gas phase container include: pressure 0-5.0 MPa, preferably 0.1-2.0 MPa; hydrogen / reaction feedstock volume ratio generally 1-2000, preferably 10-700; temperature generally 50-500℃, preferably 100-400℃.

[0015] Furthermore, the effluent from the gas phase container, after being pressurized, can be further cooled by a heat exchanger before entering the liquid phase hydrogenation reactor.

[0016] Furthermore, if the effluent from the gas phase container is not completely liquefied after pressurization, the unliquefied gas phase component is discharged upwards from the liquid phase hydrogenation reactor. The gas phase component then enters a high-pressure separator via a heat exchanger and / or condenser, thereby separating the hydrogen containing light hydrocarbons and impurities from the gas phase light component.

[0017] Furthermore, the catalyst packed in the liquid-phase hydrogenation reactor is a catalyst with selective hydrogenation function. For example, when the reactant is maleic anhydride, the selective hydrogenation catalyst A uses alumina or alumina modified with additives as a support, and a Group VIII metal and / or a Group IB metal as the active metal. The Group VIII metal is preferably nickel, and the Group IB metal is preferably copper. Based on the weight of the selective hydrogenation catalyst A, the content of the active metal, calculated by element, is as follows: the Group VIII metal content is 10%–30%, preferably 12%–20%; the Group IB metal content is 1%–15%, preferably 5%–10%. The specific surface area of ​​the selective hydrogenation catalyst A is 80–200 m². 2 / g, preferably 100-180m 2 / g, with a pore volume of 0.3-1.0 mL / g, preferably 0.4-0.6 mL / g, for example, can be a conventional Ni-Cu catalyst in the art. When the reactant is crude terephthalic acid, the selective hydrogenation catalyst B uses activated carbon or carbon material modified with additives as a support, and a Group VIII metal as the active metal, preferably ruthenium. Based on the weight of the selective hydrogenation catalyst B, the content of the active metal, calculated by element, is 1%-10%, preferably 1.5%-5.0%; the specific surface area of ​​the selective hydrogenation catalyst B is 500-1200 m² / g. 2 / g, preferably 600-1000m 2 / g, with a pore volume of 0.3 to 1.0 mL / g, preferably 0.4 to 0.8 mL / g, for example, can be a conventional rhodium-based catalyst for the hydrogenation and refining of crude terephthalic acid.

[0018] Furthermore, the operating conditions of the liquid-phase hydrogenation reactor include: pressure of 0.5–10.0 MPa, preferably 1.0–7.0 MPa; and temperature generally of 100–500 °C, preferably 100–360 °C. The pressure of the liquid-phase hydrogenation reactor is 0.5–6.0 MPa higher than the pressure of the gas-phase vessel.

[0019] Furthermore, the resulting hydrogenated heavy components are discharged from the bottom of the liquid phase reactor and preferably pass through a separator for further separation to obtain the hydrogenated product.

[0020] Furthermore, the target product obtained after separation by the separator is subjected to conventional post-processing, such as washing, filtration, and drying, to obtain the hydrogenated product.

[0021] Furthermore, the byproducts obtained after separation by the separator can be further recycled and reused.

[0022] A second aspect of the present invention provides a hydrogenation system, comprising:

[0023] A gas phase container for receiving reaction raw materials and hydrogen gas, wherein the raw materials and hydrogen gas are in a gas phase state, and the gas phase container is filled with inert packing and / or internal components that have a fluid flow distribution function.

[0024] A pressurization device used to pressurize the effluent from a gaseous container reaction.

[0025] A liquid-phase hydrogenation reactor is used to receive the pressurized gaseous container reaction effluent. The liquid-phase hydrogenation reactor is filled with a catalyst that has a hydrogenation catalytic reaction function. If the gaseous container effluent is not completely liquefied, the unliquefied gaseous component is discharged upwards from the liquid-phase hydrogenation reactor, and the liquid component is discharged downwards to contact the catalyst to carry out a liquid-phase hydrogenation reaction, resulting in hydrogenated heavy components that are discharged from the bottom of the liquid-phase hydrogenation reactor to obtain the hydrogenated product.

[0026] Furthermore, the booster device can be a conventional commercial compressor, such as a reciprocating or centrifugal compressor.

[0027] Furthermore, it also includes a high-pressure separator, which is used to separate hydrogen containing light hydrocarbons and impurities from the gas phase light component.

[0028] Furthermore, a heat exchanger I may be provided between the gas phase container and the liquid phase hydrogenation reactor to cool the effluent from the gas phase container reaction.

[0029] Furthermore, in the hydrogenation system, the liquid-phase hydrogenation reactor is also equipped with a heat exchanger II and / or a condenser. After the gaseous components are discharged upward from the liquid-phase hydrogenation reactor, they first pass through the heat exchanger II and / or the condenser, and then enter the high-pressure separator.

[0030] Compared with the prior art, the method of the present invention has the following advantages:

[0031] (1) Compared with conventional fixed-bed hydrogenation technology, the chemical reaction efficiency of this invention is significantly higher than that of traditional three-phase reaction, thus enabling the reaction to be completed under more moderate operating conditions and reducing energy consumption.

[0032] (2) Compared with liquid phase hydrogenation technology, this invention uses a phase change process of vaporization and reliquefaction of hydrogen and raw materials to enhance hydrogen dissolution, which makes up for the defects of conventional liquid phase technology, such as poor hydrogen dissolution effect of forced back-mixing of gaseous hydrogen and liquid raw materials and high cost of membrane hydrogen mixing equipment, thus achieving low-cost hydrogen dissolution and enhanced hydrogen mixing effect.

[0033] (3) In this invention, after the original reactants and hydrogen are vaporized, the macromolecules in the effluent of the gas phase container are liquefied by pressurization. Taking advantage of the higher solubility of hydrogen under high temperature conditions, the solubility of hydrogen in the liquid phase container is increased, which is beneficial to the hydrogenation reaction.

[0034] (4) When applied to the liquid-phase hydrogenation of maleic anhydride, it avoids the use of a high-cost hydrogen mixer, resulting in higher hydrogen dissolution and better reaction. When applied to the liquid-phase hydrogenation of crude terephthalic acid, it avoids the need for high-pressure conditions to ensure the product remains in the liquid phase. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the hydrogenation process of the present invention;

[0036] Wherein: 1-reaction raw materials and hydrogen, 2-gas phase container, 3-gas phase container effluent, 4-compressor, 5-liquid phase hydrogenation reactor, 6-hydrogenated heavy components, 7-gas phase light components, 8-heat exchanger, 9-condenser, 10-high pressure separator, 11-hydrogenated light components. Detailed Implementation

[0037] The present invention will be further described below with reference to the embodiments, but it should be understood that the scope of protection of the present invention is not limited to the embodiments.

[0038] In this invention, unless otherwise explicitly stated, percentages and percentage contents are all expressed by mass.

[0039] by Figure 1 The hydrogenation system and hydrogenation reaction of the present invention are illustrated as follows: The reactants and hydrogen 1 enter the gas phase container 2. Under suitable pressure, hydrogen / feed volume ratio, and temperature, all the reactants and hydrogen are vaporized. The effluent 3 from the gas phase container enters the compressor 4. After being pressurized by the compressor 4, and preferably cooled by a heat exchanger (not shown in the figure), it enters the liquid phase hydrogenation reactor 5. In the liquid phase hydrogenation reactor 5, the dissolved hydrogen liquid phase component undergoes a catalytic reaction to obtain hydrogenated heavy components 6, which are then post-processed to obtain the hydrogenated product. If the components in the liquid phase hydrogenation reactor are not completely liquefied, the unliquefied gas phase light components 7 enter the heat exchanger 8 and condenser 9, and then enter the high-pressure separator 10 to obtain hydrogenated light components 11.

[0040] The gas phase container 2 is mainly used to uniformly mix the reaction raw materials and hydrogen in the gas phase state. The reactor is filled with inert packing and / or internal components that have the function of fluid flow distribution.

[0041] Examples 1-3

[0042] Examples 1-3 used a 100 mL gas phase container and a 100 mL fixed-bed hydrogenation reactor connected in series. The gas phase mixer was filled with 50 mL of Raschig ring inert material with gas phase distribution function. The fixed-bed hydrogenation reactor was a liquid phase hydrogenation reactor, filled with 100 mL of Ni-Cu maleic anhydride hydrogenation catalyst A with high selectivity for succinic anhydride. The maleic anhydride reactant was prepared into a 12% solution using γ-butyrolactone as the solvent. The catalyst properties are shown in Table 1, the feedstock oil properties are shown in Table 2-1, and the reaction process conditions and results are shown in Table 3.

[0043] Comparative Example 1

[0044] A conventional maleic anhydride liquid-phase hydrogenation process was adopted, with two hydrogenation reactors (a conventional maleic anhydride hydrogenation process involves two reactors), designated Reactor 1 and Reactor 2. Both reactors were equipped with high-efficiency ceramic membrane tube hydrogen mixers. Both reactors were loaded with a Ni-Cu catalyst A, which has high selectivity for succinic anhydride, at a loading volume of 50 mL. A normal separation process was implemented downstream of the reactors. The properties of the feedstock and catalyst were the same as in Examples 1-3, and the reaction conditions and results are shown in Table 3.

[0045] Examples 4-6

[0046] Examples 4-6 used a 100 mL gas-phase container and a 100 mL fixed-bed hydrogenation reactor connected in series. The gas-phase container was filled with 50 mL of Raschig ring inert material with gas-phase distribution function. The fixed-bed reactor was a liquid-phase hydrogenation reactor, filled with 100 mL of terephthalic acid selective hydrogenation catalyst B. The reactant was crude terephthalic acid, which was mixed with demineralized water to prepare a 25% solution before entering the gas-phase container. The catalyst properties are shown in Table 1, the feed oil properties are shown in Tables 2-2, and the reaction process conditions and results are shown in Table 4.

[0047] Comparative Example 2

[0048] A conventional liquid-phase hydrogenation process for terephthalic acid was adopted, with one hydrogenation reactor, designated Reactor 1. Reactor 1 was filled with 100 mL of terephthalic acid selective hydrogenation catalyst B. A normal separation process was then established downstream of the reactor. The properties of the raw materials and catalyst were the same as in Examples 4-6, and the reaction conditions and results are shown in Table 4.

[0049] Table 1. Physicochemical properties of catalysts

[0050]

[0051]

[0052] Table 2-1 Properties of Raw Materials

[0053] Raw material properties maleic anhydride Content (based on maleic anhydride mass) / % ≥99.5 Sulfur / ppm ≤1 chlorine / ppm ≤1 Phosphorus / ppm ≤1 Ash content / ppm ≤10 <![CDATA[Iron (Fe 2+ , Fe 3+ ) / ppm]]> ≤2

[0054] Table 2-2 Properties of Raw Materials

[0055]

[0056] Table 3 Process conditions and results

[0057]

[0058]

[0059] As can be seen from Examples 1-3, compared with Comparative Example 1, the present invention can replace the use of high-cost ceramic membrane hydrogen mixers in traditional liquid-phase hydrogenation technology. Furthermore, by using inert materials in the gas phase container to better disperse hydrogen and raw materials, it promotes the subsequent dissolution of hydrogen, which is beneficial to the hydrogenation conversion rate in the liquid-phase hydrogenation reactor, and the purity of the product succinic anhydride can reach 99%. Comparative Example 2 uses a pressurization method to dissolve hydrogen. Due to the limited pressurization space, the hydrogen dissolution effect is poor, and the reaction effect is unsatisfactory.

[0060] Table 4 Process conditions and results

[0061] Example 4 Example 5 Example 6 Comparative Example 2 Gas Phase Vessel / Reactor 1 Pressure, MPa 0.2 0.2 0.2 7.0 Temperature, °C 350 360 370 300 Hydrogen-to-oil ratio, v / v 20 20 20 20 <![CDATA[Space velocity, h -1 > - - 1.0 Liquid phase hydrogenation reactor / reactor 2 Pressure, MPa 3.0 4.0 5.0 - Temperature, °C 280 290 300 - <![CDATA[Space velocity, h -1 > 1.0 1.0 1.0 - Product Nature p-Toluenebenzoic acid / ppm 106 88 63 157 p-Carboxybenzaldehyde / ppm 20 18 15 29

[0062] As can be seen from Examples 4-6, compared with Comparative Example 2, the present invention allows for reaction at a lower reaction pressure, increasing the safety of the entire reaction system. Furthermore, the use of an inert environment within the gas phase container better disperses hydrogen and raw materials, promoting subsequent hydrogen dissolution and improving the hydrogenation conversion rate in the liquid phase hydrogenation reactor, resulting in better reaction performance.

Claims

1. A hydrogenation method, characterized in that... Includes the following steps: The reactants and hydrogen first enter the gas phase container and become gaseous. The gas phase container is filled with inert packing and / or internal components that have a fluid flow distribution function. The effluent from the gas phase container is pressurized and enters the liquid phase hydrogenation reactor. The hydrogenation reaction takes place in the liquid phase hydrogenation reactor. The hydrogenated heavy components are discharged from the bottom of the liquid phase hydrogenation reactor, and finally the hydrogenated product is obtained. The reaction raw materials are at least one of maleic anhydride and crude terephthalic acid; The operating conditions of the gas phase container include: pressure of 0.1~2.0MPa, hydrogen / reactant volume ratio of 10~700, and temperature of 100~400℃; The operating conditions of the liquid-phase hydrogenation reactor include: pressure of 1.0~7.0 MPa and temperature of 100~360℃; the pressure of the liquid-phase hydrogenation reactor is 0.5~6.0 MPa higher than the pressure of the gas phase vessel. The internal components are gas-phase distribution trays; the inert packing is ceramic balls and / or Raschig rings.

2. The method according to claim 1, characterized in that, The reaction raw material is maleic anhydride.

3. The method according to claim 2, characterized in that, When maleic anhydride is used as a reaction raw material, γ-butyrolactone is used as a solvent, and a maleic anhydride solution with a mass concentration of 10%~20% is prepared based on the mass of maleic anhydride for feeding.

4. The method according to claim 1, characterized in that, When crude terephthalic acid is used as the reaction raw material, demineralized water is used as the solvent, and a crude terephthalic acid solution with a mass concentration of 20% to 35% is prepared based on the mass of crude terephthalic acid for feeding.

5. The method according to any one of claims 1-4, characterized in that, The hydrogenation system used in the hydrogenation method includes: A gas phase container for receiving reactants and hydrogen, wherein the reactants and hydrogen are in a gas phase state, and the gas phase container is filled with inert packing and / or internal components that have a fluid flow distribution function. A pressurization device used to pressurize the effluent from a gaseous container reaction. A liquid-phase hydrogenation reactor is used to receive the pressurized gaseous container reaction effluent. The liquid-phase hydrogenation reactor is filled with a catalyst that has a hydrogenation catalytic reaction function. If the gaseous container effluent is not completely liquefied, the unliquefied gaseous component is discharged upwards from the liquid-phase hydrogenation reactor, and the liquid component is discharged downwards to contact the catalyst to carry out a liquid-phase hydrogenation reaction, resulting in hydrogenated heavy components that are discharged from the bottom of the liquid-phase hydrogenation reactor to obtain the hydrogenated product.

6. The method according to claim 5, characterized in that, The effluent from the gas phase container is pressurized, cooled by a heat exchanger, and then enters the liquid phase hydrogenation reactor.

7. The method according to claim 5, characterized in that, The liquid phase hydrogenation reactor is also equipped with heat exchanger II. After the gas phase components are discharged upward from the liquid phase hydrogenation reactor, they first pass through heat exchanger II and then enter the high pressure separator.

8. The method according to claim 5, characterized in that, The liquid-phase hydrogenation reactor is also equipped with a condenser. After the gaseous components are discharged upward from the liquid-phase hydrogenation reactor, they first pass through the condenser and then enter the high-pressure separator.

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