Process for producing cyclopentanone from cyclopentene

Abstract

The invention provides a process for producing cyclopentanone from cyclopentene, and belongs to the technical field of cyclopentanone production.In the esterification reaction, acetic acid is used for removing metal ions to improve the activity stability of a sulfonic cation exchange resin catalyst; when the ester hydrogenation process is used, the cyclopentyl acetate is directly converted into cyclopentanol and absolute ethyl alcohol with high added value; the appropriate CuO-ZnO / Al2O3 high-activity dehydrogenation catalyst is selected, so that the reaction efficiency is obviously improved, the energy consumption is obviously reduced, the conversion per pass of the dehydrogenation reaction is 70% or above, and the selectivity of cyclopentanone is close to 100%. In short, the production method provided by the invention is high in catalyst activity, high in reaction conversion rate, short in reaction time, relatively easy in product refining and cyclopentanol recovery, obviously reduced in energy consumption and more suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of cyclopentanone production technology, and more specifically to a process for producing cyclopentanone from cyclopentene. Background Technology

[0002] Cyclopentanone is an intermediate in the fragrance and pharmaceutical industries, used to produce novel fragrances such as methyl dihydrojasmonate and vanillin, as well as fine chemical products like the anti-anxiety drug buspirone. It is also used in the synthesis of pesticides such as insecticides and herbicides. Furthermore, due to its excellent solubility, cyclopentanone is widely used as a solvent in the electronics industry.

[0003] Cyclopentene, obtained from the C5 fraction of naphtha cracking for ethylene production, can be used as a raw material to produce cyclopentanone. The main processes include the direct N2O oxidation of cyclopentene and the cyclopentene hydration-dehydrogenation method. While the direct N2O oxidation process has been industrialized, it is geographically limited and requires a supporting N2O oxidant production unit to significantly reduce production costs. The cyclopentanone production route, which involves hydrating cyclopentene to obtain cyclopentanol and then dehydrogenating it, is an environmentally friendly approach with significant advantages in both technology and economics.

[0004] Japanese Patent JP2003212803 proposes a method for hydrating cyclopentene to produce cyclopentanol using a strongly acidic cation exchange resin. It is reported that under the condition that the molar ratio of water to cyclopentene is 1.2 to 3.0, the single-pass conversion rate of cyclopentene is about 3.50%, and the selectivity is about 98%.

[0005] Chinese invention patent application CN102399132A discloses a method for preparing cyclopentanol from cyclopentene, comprising the following steps: 1) Cyclopentene and acetic acid undergo an addition reaction in the liquid phase via a fixed-bed catalyst to generate cyclopentyl acetate. The molar ratio of cyclopentene to acetic acid is 1:2-5, and the liquid hourly space velocity is 1-3 h⁻¹. -1 The reaction temperature was 50–80℃, the reaction pressure was 0.2–0.7 MPaG, and the catalyst was a sulfonic acid-based cation exchange resin with a mass exchange capacity of 3–5.5 mmol / g; 2) The addition reaction product was separated by distillation to obtain purified cyclopentyl acetate; 3) The purified cyclopentyl acetate was reacted with methanol in the liquid phase through a fixed-bed catalyst to undergo transesterification to produce cyclopentanol and methyl acetate. The molar ratio of cyclopentyl acetate to methanol was 1:2–5, and the liquid hourly space velocity was 0.8–2 h⁻¹. -1 The reaction temperature is 40-60℃, the reaction pressure is 0.1-0.5MPaG, the catalyst is sulfonic acid-based cation exchange resin, and the mass exchange capacity of the resin is 3-5.5mmol / g; 4) The transesterification reaction product is separated by distillation to obtain the product cyclopentanol and the byproduct methyl acetate.

[0006] Chinese invention patent application CN102603486A discloses a method for preparing cyclopentanol from cyclopentene, comprising the following steps: 1) mixing cyclopentene and acetic acid, and then carrying out an esterification reaction in the liquid phase through a catalyst bed to convert cyclopentene and acetic acid into cyclopentyl acetate. The molar ratio of acetic acid to cyclopentene is 2-5:1, and the mass hourly space velocity is 1-3 h⁻¹. -1 The reaction temperature is 50–80℃, the reaction pressure is 0.1–0.5 MPa, and the catalyst is a sulfonic acid-based cation exchange resin; 2) The above reaction solution is distilled in a distillation column with 25 theoretical plates. Unreacted cyclopentene and acetic acid are recovered from the top of the distillation column and recycled. The crude cyclopentyl acetate obtained from the bottom of the column is directly used as the raw material for the transesterification reaction; 3) Methanol is dehydrated using a 3A molecular sieve to reduce the water content of methanol to below 10 ppm; 4) Crude cyclopentyl acetate and dehydrated methanol are mixed and transesterified under the action of CaO catalyst to obtain cyclopentanol; the mass ratio of methanol to cyclopentyl acetate is 0.8-2.0:1; the amount of CaO catalyst is 1-3% of the mass of cyclopentyl acetate, the catalyst is CaO particles with a particle size of 0.03-0.05 mm, and the transesterification reaction temperature is 60-90℃; the transesterification reaction byproduct methyl acetate is discharged in the gas phase and directly enters the distillation column and is separated from the top of the distillation column, and the reflux ratio of the distillation is controlled to be 1-4:1.

[0007] Chinese invention patent application CN102617290A describes a method for preparing cyclopentanol from cyclopentene, including the following steps: 1) Mixing cyclopentene and acetic acid, and then carrying out an esterification reaction in the liquid phase through a catalyst bed to convert cyclopentene and acetic acid into cyclopentyl acetate. The molar ratio of acetic acid to cyclopentene is 2-5:1, and the mass hourly space velocity is 1-3 h⁻¹. -1 The reaction temperature is 50–80℃, the reaction pressure is 0.1–0.5 MPa, and the catalyst is a sulfonic acid-based cation exchange resin; 2) The above reaction solution is distilled in a distillation column with 25 theoretical plates; under atmospheric pressure, unreacted cyclopentene and acetic acid are recovered from the top of the distillation column and recycled, and the crude cyclopentyl acetate obtained from the bottom of the column is directly used as the transesterification feedstock; 3) Crude cyclopentyl acetate and methanol are mixed and transesterified through a catalyst bed composed of granular CaO to obtain cyclopentanol; the molar ratio of methanol to cyclopentyl acetate is 2–5:1, and the mass hourly space velocity is 1–2 h⁻¹. -1 The acid exchange reaction temperature is 60–90℃, the reaction pressure is 0.01–0.05 MPa, and the catalyst is CaO particles with a particle size of 3–5 mm.

[0008] Chinese invention patent application CN102603486A discloses a method for preparing cyclopentanol from cyclopentene. The method includes the following steps: 1) mixing cyclopentene and acetic acid, and then passing the mixture in the liquid phase through a catalyst bed composed of sulfonic acid-based cation exchange resin for esterification reaction, so that cyclopentene and acetic acid are converted into cyclopentyl acetate. The molar ratio of acetic acid to cyclopentene is 2–5:1, and the mass hourly space velocity (HHSV) is 1–3 h⁻¹. -1 The reaction temperature was 50–80℃, and the reaction pressure was 0.1–0.5 MPa. 2) The above reaction solution was distilled in a distillation column with 25 theoretical plates. Unreacted cyclopentene and acetic acid were recovered from the top of the distillation column and recycled. The crude cyclopentyl acetate obtained from the bottom of the column was directly used as the raw material for the transesterification reaction. 3) Methanol was dehydrated using a 3A molecular sieve to reduce the water content to below 10 ppm. 4) Crude cyclopentyl acetate and methanol were mixed and transesterified to obtain cyclopentanol. The mass ratio of methanol to cyclopentyl acetate was 0.8–2.0:1, and the amount of CaO catalyst added was 1–3% of the mass of cyclopentyl acetate. In the esterification reaction, the conversion rate of cyclopentene was 87.2%, and the selectivity of cyclopentyl acetate was above 99%.

[0009] Chinese invention patent CN105461515B discloses a method for preparing cyclopentanol from cyclopentene, comprising the following steps: 1) mixing cyclopentene and acetic acid, and then carrying out an esterification reaction in the liquid phase through a catalyst bed to convert cyclopentene and acetic acid into cyclopentyl acetate. The molar ratio of acetic acid to cyclopentene is 4-8:1, and the mass hourly space velocity is 1-3 h⁻¹. -1 The reaction temperature is 40–50℃, the reaction pressure is 0.1–0.5 MPa, and the catalyst is a sulfonic acid-based cation exchange resin modified with cerium nitrate, with the cerium ion exchange capacity being 10–30% of the mass exchange capacity of the sulfonic acid-based cation exchange resin; 2) The above reaction solution is distilled in a distillation column with 25 theoretical plates; under normal pressure, unreacted cyclopentene and acetic acid are recovered from the top of the distillation column and recycled, and the crude cyclopentyl acetate obtained from the bottom of the column is directly used as the raw material for the transesterification reaction; 3) The transesterification reaction is carried out in… The reaction is carried out in a reactive distillation column with a fixed-bed reactor connected in parallel to the bottom. A mixture of crude cyclopentyl acetate and methanol is fed into the bottom of the distillation column. The material is first pumped from the bottom of the fixed-bed reactor through a fixed-bed bed of granular CaO (5–10 mm in diameter) for dehydration pretreatment. The pretreated material is then returned to the bottom of the distillation column. Once the water content in the reaction solution is reduced to less than or equal to 10 ppm, a sodium methoxide / methanol solution catalyst is added via pump to initiate the transesterification reaction. The pretreatment mass hourly space velocity (HHSV) is 0.5–5.0 h⁻¹. -1The mass ratio of methanol to cyclopentyl acetate is 0.8–2.0:1, the amount of sodium methoxide catalyst is 0.1–1% of the mass of cyclopentyl acetate, and the transesterification reaction temperature is 60–90℃. The transesterification reaction byproduct methyl acetate is discharged in the gas phase and directly enters the distillation column and is separated from the top of the distillation column. The reflux ratio of the distillation is controlled to be 1–4:1.

[0010] Chinese invention patents CN1249008C and CN1260195C disclose a method for preparing cyclopentanone from catalytic distillation of cyclopentanol. The raw material cyclopentanol is directly converted to high-purity cyclopentanone via catalytic dehydrogenation distillation. The dehydrogenation reaction temperature is 130–140℃, the reaction pressure is atmospheric pressure, and granular Raney nickel-type metal alloy is used as the catalyst. The dehydrogenation product is discharged as a gas and directly purified by distillation. The purity of cyclopentanol is generally 98%, but the cyclopentanol loading (WWH) of the catalyst is only 0.3–1.5 hr. -1 However, the catalyst has low efficiency and still consumes a lot of energy.

[0011] In summary, the existing methods for producing cyclopentanone from cyclopentene mainly have the following problems:

[0012] 1. A sulfonic acid-based strong acid cation exchange resin is used as a catalyst for the esterification reaction between cyclopentene and acetic acid. Unlike the normal decline in activity of general catalysts over time, the activity of this resin catalyst shows accelerated deactivation as the operating time increases.

[0013] 2. In the transesterification of cyclopentyl acetate and methanol to produce cyclopentanol, readily hydrolyzable CaO is used as a dehydrating agent or catalyst, or the transesterification reaction is carried out using CaO dehydration and sodium methoxide / methanol solution as a catalyst. Because CaO becomes a viscous slurry when it absorbs water and transforms into Ca(OH)2, it severely blocks the CaO bed and makes the separation of the reactants from Ca(OH)2 very difficult. Furthermore, the separated Ca(OH)2 slurry contains volatile organic compounds, causing serious environmental pollution.

[0014] 3. The dehydrogenation of cyclopentanol using catalytic distillation has low catalyst efficiency and high energy consumption. Summary of the Invention

[0015] To address the technical shortcomings of existing processes for producing cyclopentanone from cyclopentene, this invention provides a process for producing cyclopentanone from cyclopentene, featuring high catalyst activity, short reaction time, high conversion rate, relatively easy product purification and cyclopentanol recovery, significantly reduced energy consumption, and greater suitability for industrial production.

[0016] A process for producing cyclopentanone from cyclopentene includes the following steps:

[0017] 1. Acetic acid pretreatment

[0018] According to the national standard GB / T1628-2008 for industrial glacial acetic acid, the Fe ion content in acetic acid should typically be less than or equal to 0.4 ppm, 2 ppm, and 4 ppm, respectively. For Fe ions, the maximum Fe ion threshold that a strongly acidic cation exchange resin can withstand is 0.5 ppm. When the Fe ion content in the esterification reaction solution exceeds 0.5 ppm, Fe ions will exchange with –SO3 on the resin surface, thus affecting the catalyst activity. Generally, due to the strong corrosiveness of acetic acid, even though all equipment is made of corrosion-resistant materials, the recovered acetic acid still contains 1-15 ppm of metal ions after distillation. Therefore, this invention first pretreats the acetic acid to remove metal ions, thereby improving the activity stability of the sulfonic acid-based cation exchange resin catalyst during the esterification reaction, reducing the catalyst activity decay rate, extending the catalyst's lifespan, and reducing production costs.

[0019] Fresh and / or recycled acetic acid is passed through the first catalyst bed to remove metal ions at a mass hourly space velocity (WHSV) of 1–3 h⁻¹. -1 The reaction temperature is 0–50℃, the reaction pressure is 0.0–atmospheric pressure, the catalyst is sulfonic acid-based cation exchange resin, and the metal ion content of the treated acetic acid is ≤0.5ppm.

[0020] Preferably, the mass hourly space velocity (MHSV) is 1.5–2.5 h⁻¹. -1 The reaction temperature is 25–40°C, and the reaction pressure is atmospheric pressure.

[0021] 2. Esterification: Cyclopentene and acetic acid with metal ions removed are mixed and then passed through a second catalyst bed in the liquid phase to carry out the esterification reaction, resulting in an esterification reaction solution.

[0022] The molar ratio of acetic acid to cyclopentene is 2–4:1, and the mass hourly space velocity (HHSV) is 1–3 h⁻¹. -1 The reaction temperature is 40–70℃, the reaction pressure is 0.2–0.8 MPa, and the catalyst is a sulfonic acid-based cation exchange resin; preferably, the molar ratio of acetic acid to cyclopentene is 2.5–3.5:1; and the mass hourly space velocity (WHSV) is 1.5–2.5 h⁻¹. -1 The reaction temperature is 50–65℃, and the reaction pressure is 0.3–0.5 MPa; the mass exchange capacity of the sulfonic acid-based cation exchange resin is 3.5–5.0 mmol / g.

[0023] 3. Cyclopentene recovery: The esterification reaction liquid is distilled, and the bottom liquid is collected under normal pressure. Unreacted cyclopentene is recovered from the top of the column and recycled to the esterification process in step 2.

[0024] 4. Acetic acid recovery: The bottom liquid of the column is distilled under reduced pressure to recover excess acetic acid from the top of the column. After the acetic acid pretreatment process in step 1, it is recycled to the esterification process in step 2 to obtain cyclopentyl acetate from the bottom of the column.

[0025] 5. Ester hydrogenation: Cyclopentyl acetate is mixed with hydrogen gas and then hydrogenated through a Cu-Zn-Cr / Al2O3 fixed-bed catalyst bed to produce hydrogenated materials.

[0026] The hydrogen-ester molar ratio is 20–60:1, and the mass hourly space velocity (HHSV) of the hydrogenation reaction is 0.1–0.5 h⁻¹. -1 The system pressure is 40–65 bar, and the reaction temperature is 180–230 °C.

[0027] The ester hydrogenation process directly hydrogenates cyclopentyl acetate to cyclopentanol, and the byproduct, anhydrous ethanol, has a higher added value compared to methyl acetate. Due to the inherently environmentally friendly nature of the hydrogenation process, compared with other processes, the ester hydrogenation process significantly reduces production costs while completely eliminating the generation of waste.

[0028] 6. Ethanol recovery: The hydrogenated material is fed into a distillation column, and anhydrous ethanol with a purity of over 99.5% is collected from the top of the column, while cyclopentanol is obtained from the bottom of the column.

[0029] 7. Dehydrogenation: Cyclopentanol is dehydrogenated to cyclopentanone via a CuO-ZnO / Al2O3 fixed-bed catalyst bed. The CuO-ZnO / Al2O3 catalyst has a particle size of ψ5×4.5~5.2mm, and the mass hourly space velocity (WHSV) of the dehydrogenation reaction is 0.2~1.0 hr. -1 The system pressure is 0.0–0.5 bar, and the reaction temperature is 200–260 °C. Preferably, cyclopentanol can be dehydrogenated using a fixed-bed gas-phase process.

[0030] The CuO-ZnO / Al2O3 catalyst was selected for the dehydrogenation of cyclopentanol. This catalyst has high activity, which can carry out the reaction at a suitable temperature, thereby effectively avoiding the cyclopentanone dimerization side reaction and improving the reaction yield. At the same time, a simple fixed-bed reactor can be used for dehydrogenation, simplifying the reaction process. Furthermore, due to its high single-pass conversion rate, product purification and cyclopentanol recovery are relatively easy, and energy consumption is significantly reduced.

[0031] In the esterification reaction, this invention improves the activity and stability of the sulfonic acid-based cation exchange resin catalyst by using acetic acid to remove metal ions; in the ester hydrogenation process, cyclopentyl acetate is directly converted into cyclopentanol and anhydrous ethanol with higher added value; by selecting a suitable CuO-ZnO / Al2O3 highly active dehydrogenation catalyst, the reaction efficiency is significantly improved, the energy consumption is significantly reduced, the single-pass conversion rate of the dehydrogenation reaction is above 70%, and the selectivity of cyclopentanone is close to 100%.

[0032] In summary, the production method provided by this invention features a catalyst with high activity, high reaction conversion rate, short reaction time, relatively easy product purification and cyclopentanol recovery, and significantly reduced energy consumption, making it more suitable for industrial production. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical applications of the invention, and to enable those skilled in the art to understand the invention and design various embodiments with various modifications suitable for a particular purpose.

[0034] In this invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0035] In the examples, the conversion rate and selectivity of each reaction are defined as follows:

[0036] 1. ;

[0037] ;

[0038] 3. ;

[0039] 4. ;

[0040] 5. ;

[0041] 6. .

[0042] Example 1

[0043] 1. Acetic acid pretreatment

[0044] Acetic acid pretreatment was carried out in a tubular fixed-bed reactor with dimensions of φ25mm×1500mm. 100g of spherical sulfonic acid-based cation exchange resin catalyst with a particle size of 0.40~1.25mm was charged into the reactor to form a fixed-bed catalyst bed, with a resin mass exchange capacity of 5.0mmol / g.

[0045] Fresh and recycled acetic acid is passed through a sulfonic acid-based cation exchange resin catalyst bed, where metal ions entrained in the acetic acid are removed by ion exchange at a mass hourly space velocity (WHSV) of 1–3 h⁻¹. -1The reaction temperature was 0–50℃, the reaction pressure was 0.0–0.1 MPa, and the metal ion content of the treated acetic acid was ≤0.5 ppm. The reaction conditions and results are shown in Table 1.

[0046] Table 1

[0047]

[0048] 2. Esterification reaction

[0049] The esterification reaction was carried out in a tubular fixed-bed reactor with dimensions of φ25mm × 1500mm. 100g of spherical sulfonic acid-based cation exchange resin catalyst with a particle size of 0.40–1.25mm was charged into the reactor to form a fixed-bed catalyst bed, with a resin mass exchange capacity of 5.0 mmol / g. The reactor was externally equipped with a circulating hot water temperature control jacket, and platinum resistance thermometers were installed at the top, middle, and bottom of the catalyst bed. The reaction feed rate was controlled by a feed pump, and the system pressure was regulated by a back pressure valve.

[0050] Cyclopentene and acetic acid (with metal ions removed) are mixed and then esterified in the liquid phase through a catalyst bed to convert cyclopentene and acetic acid into cyclopentyl acetate. In the esterification reaction, acetic acid with a metal ion content ≤0.5 ppm is used as the reactant, the molar ratio of acetic acid to cyclopentene is 2–4:1, and the mass hourly space velocity (HHSV) is 1–3 h⁻¹. -1 The reaction temperature was 40–70℃, the reaction pressure was 0.2–0.8 MPa, and the catalyst was a sulfonic acid-based cation exchange resin. The esterification product, cyclopentyl acetate, was analyzed by chromatography, and the conversion rate and product selectivity were calculated. The reaction conditions and results are shown in Table 2.

[0051] Table 2

[0052]

[0053] 3. Ester hydrogenation reaction

[0054] The hydrogenation reactor is a stainless steel tubular reactor with dimensions of φ25mm × 1000mm. 100ml of catalyst, specifically Cu-Zn-Cr / Al2O3 hydrogenation catalyst with a particle size of ψ5 × 4.5–5.2mm, is packed into the reactor. Inert ceramic balls are placed at the bottom of the reactor. The preheated dehydrogenation feedstock is pumped into the reactor from the top through a distributor at a set rate for the hydrogenation reaction. The hydrogenated material enters a gas-liquid separator from the bottom of the reactor, while the liquid phase enters a product storage tank. The system pressure is controlled by a hydrogen regulating valve from the gas-liquid separator. Specific reaction conditions, the conversion rate of cyclopentanol acetate in the hydrogenation reaction, and the selectivity of cyclopentanol are listed in Table 3.

[0055] Table 3

[0056]

[0057] 4. Dehydrogenation

[0058] The dehydrogenation reactor is a stainless steel tubular reactor with dimensions of φ25mm × 1000mm. 100ml of catalyst, specifically CuO-ZnO / Al2O3 dehydrogenation catalyst with a particle size of ψ5×4.5~5.2mm, is packed into the reactor. Inert ceramic balls are packed at the bottom of the reactor. The preheated dehydrogenation feedstock is pumped into the reactor from the top through a distributor at a set rate for the dehydrogenation reaction. The dehydrogenated material enters a gas-liquid separator from the bottom of the reactor, while the liquid phase enters a product storage tank. The system pressure is controlled by a hydrogen regulating valve from the gas-liquid separator. Specific reaction conditions, cyclopentanol conversion rate, and cyclopentanone selectivity in the dehydrogenation reaction are listed in Table 4.

[0059] Table 4

[0060]

[0061] As can be seen from Table 4, the dehydrogenation reaction efficiency is significantly improved and the energy consumption is significantly reduced (comparable to Chinese invention patents CN1249008C and CN1260195C). The single-pass conversion rate is over 70%, and the selectivity of cyclopentanone is close to 100%.

[0062] Comparative Example 1

[0063] Using the same experimental setup, acetic acid with a content of 5-10 ppm was used as the esterification raw material, and compared with acetic acid with a metal ion content of less than 0.5 ppm as the esterification raw material. The effect of metal ions in acetic acid on the stability of the catalyst was characterized by examining the relationship between running time and cyclopentene conversion rate.

[0064] The reaction conditions are shown in Table 2, reaction condition 15, namely, the molar ratio of acetic acid to cyclopentene is 2.5:1, and the mass hourly space velocity (HHSV) is 2.0 h⁻¹. -1 The reaction temperature was 55℃, and the reaction pressure was 0.4 MPa. Samples were taken and analyzed as required during the running time. The comparison results between this comparative example and reaction condition 15 are shown in Table 5.

[0065] Table 5

[0066]

[0067] As can be seen from Table 5, when using acetic acid with a content of 5-10 ppm as the esterification raw material, the esterification conversion rate shows a decreasing trend as the operating time increases. After the acetic acid is treated to remove metal ions, the activity stability of the sulfonic acid-based cation exchange resin catalyst is improved, the catalyst activity decay rate is reduced, and the catalyst service life is extended.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for producing cyclopentanone from cyclopentene, characterized in that, Includes the following steps: Step 1, Acetic acid pretreatment: Fresh and / or recycled acetic acid is passed through the first catalyst bed to remove metal ions at a mass hourly space velocity (WHSV) of 1–3 h⁻¹. -1 The reaction temperature is 0–50℃, the reaction pressure is 0.0–atmospheric pressure, the catalyst is sulfonic acid-based cation exchange resin, and the metal ion content of acetic acid after treatment is ≤0.5ppm; Step 2, esterification: Cyclopentene and acetic acid with metal ions removed are mixed and then passed through the second catalyst bed in liquid phase to carry out the esterification reaction to obtain the esterification reaction solution; The molar ratio of acetic acid to cyclopentene is 2–4:1, and the mass hourly space velocity (HHSV) is 1–3 h⁻¹. -1 The reaction temperature is 40–70℃, the reaction pressure is 0.2–0.8 MPa, and the catalyst is a sulfonic acid-based cation exchange resin. Step 3, cyclopentene recovery: The esterification reaction liquid is distilled, and the bottom liquid is collected under normal pressure. Unreacted cyclopentene is recovered from the top of the column and recycled to the esterification process in Step 2. Step 4, Acetic acid recovery: The bottom liquid of the column is distilled and excess acetic acid is recovered from the top of the column under reduced pressure. After the acetic acid pretreatment process in Step 1, it is recycled to the esterification process in Step 2 to obtain cyclopentyl acetate from the bottom of the column. Step 5, Ester hydrogenation: Cyclopentyl acetate is mixed with hydrogen gas and then hydrogenated through a Cu-Zn-Cr / Al2O3 fixed-bed catalyst bed to produce hydrogenated material; The hydrogen-ester molar ratio is 20–60:1, and the mass hourly space velocity (HHSV) of the hydrogenation reaction is 0.1–0.5 h⁻¹. -1 The system pressure is 40–65 bar, and the reaction temperature is 180–230 °C. Step 6, Ethanol recovery: The hydrogenated material is fed into a distillation column, and anhydrous ethanol with a purity of 99.5% or higher is collected from the top of the column, while cyclopentanol is obtained from the bottom of the column. Step 7, Dehydrogenation: Cyclopentanol is dehydrogenated to cyclopentanone via a CuO-ZnO / Al2O3 fixed-bed catalyst bed. The mass hourly space velocity (WHSV) of the dehydrogenation reaction is 0.2–1.0 hr. -1 The system pressure is 0.0–0.5 bar, and the reaction temperature is 200–260 °C.

2. The process for producing cyclopentanone from cyclopentene according to claim 1, characterized in that, In step 1, the mass hourly space velocity (MHSV) is 1.5–2.5 h⁻¹. -1 The reaction temperature is 25–40°C, and the reaction pressure is atmospheric pressure.

3. The process for producing cyclopentanone from cyclopentene according to claim 1, characterized in that, In step 2, the molar ratio of acetic acid to cyclopentene is 2.5–3.5:1; the mass hourly space velocity (HHSV) is 1.5–2.5 h⁻¹. -1 The reaction temperature is 50–65℃, and the reaction pressure is 0.3–0.5 MPa; the mass exchange capacity of the sulfonic acid-based cation exchange resin is 3.5–5.0 mmol / g.

4. The process for producing cyclopentanone from cyclopentene according to claim 1, characterized in that, In step 5, the mass hourly space velocity (MHV) is 0.2–0.4 h⁻¹. -1 The system pressure is 50–60 bar, the reaction temperature is 190–220 °C, and the hydrogen-ester molar ratio is 30–50.

5. The process for producing cyclopentanone from cyclopentene according to claim 1, characterized in that, In step 7, the mass hourly space velocity is 0.3–0.8 hr. -1 The system pressure is 0.08–0.30 bar, and the reaction temperature is 230–250 °C.

6. The process for producing cyclopentanone from cyclopentene according to claim 1, characterized in that, In step 7, cyclopentanol is dehydrogenated using a fixed-bed gas-phase process.

7. The process for producing cyclopentanone from cyclopentene according to claim 1, characterized in that, The CuO-ZnO / Al2O3 catalyst has a particle size of ψ5×4.5~5.2mm.

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