Process for filtering and recovering cyclohexene hydration catalyst

Abstract

The invention discloses a cyclohexene hydration catalyst filtration and recovery process, which comprises the following steps: carrying out cyclohexanol separation, membrane filtration concentration and catalyst recovery treatment on a reaction solution containing a hydration catalyst, recovering the hydration catalyst in the reaction solution, carrying out membrane filtration concentration to obtain a filtrate, and refining the filtrate with cyclohexanol to obtain refined cyclohexanol. The hydration catalyst in the cyclohexanol separation tower kettle liquid is filtered and intercepted in a membrane separation mode, the cyclohexanol reaction liquid is purified, and the post-treatment process is simplified. The catalyst provided by the invention has the advantages of good interception effect, small modification on the existing production device, small occupied area of equipment, low equipment investment, low operation cost and remarkable economic benefit.

Description

Technical Field

[0001] The present invention relates to the field of catalyst filtration, concentration, and recovery, and more specifically to a new process for recovering cyclohexanol hydration catalysts. By employing membrane filtration, concentration, and recovery techniques, the process avoids catalyst loss, purifies the cyclohexanol hydration reaction liquid, simplifies the post-processing process, and achieves significant energy savings. Background Art

[0002] Cyclohexanol is an important organic chemical with the chemical formula C6H12O. Its main use is in the production of nylon 6 and nylon 66. In addition, cyclohexanol can also be used in disinfectants, fragrances, insecticides, fungicides, leather softeners and wood preservatives.

[0003] In existing cyclohexene hydration processes for producing cyclohexanol, the vast majority of the hydration catalyst in the reactor remains in the reactor due to gravity settling. However, trace amounts of catalyst still enter the subsequent product separation equipment with the hydration reaction liquid. To prevent this catalyst from accumulating during the product concentration process, potentially clogging the equipment and affecting normal operation, the catalyst-containing bottoms liquid exiting the cyclohexanol separation tower is heated, vaporized, and then recondensed to remove the catalyst from the feed liquid. The catalyst is concentrated and discharged from the system along with the concentrated residual liquid, which then enters the cyclohexanol purification tower. This process involves significant heat loss during the catalyst removal process, as well as losses in the reaction liquid during the catalyst removal process through the evaporation of the residual liquid.

[0004] To address these issues, domestic and international institutions have conducted extensive research on removing catalyst from cyclohexanol hydration reaction liquid. In Chinese patent CN215610593U, the hydration reaction liquid is first treated by coarse filtration, followed by fine filtration of the cyclohexanol separation tower bottom liquid. The solids and liquids obtained from the two interceptions are mixed and discharged from the system. The coarse filtration recovery vessel and the fine filtration recovery vessel are equipped with ceramic filter membranes. In Chinese patent CN110327678B, the catalyst in the hydration reaction liquid is enriched by gravity. The upper liquid layer enters a cyclohexene separation tower, and the catalyst-rich lower layer is filtered to intercept the catalyst. The filtrate is then extracted to recover the cyclohexanol. Summary of the Invention

[0005] The present invention provides a cyclohexene hydration catalyst filtration and recovery process, which filters and intercepts the hydration catalyst in the bottom liquid of a cyclohexanol separation tower by membrane separation, purifies the cyclohexanol reaction liquid, simplifies the post-treatment process, requires little modification to existing production equipment, occupies a small equipment footprint, has low equipment investment and operating costs, and has good catalyst retention effect and significant economic benefits.

[0006] The specific implementation scheme of the present invention is as follows: Cyclohexanol separation tower: The reaction liquid containing the hydration catalyst is distilled, and the light components are discharged from the top of the distillation tower, and the bottom liquid containing the catalyst enters the membrane filtration concentration device; Membrane filtration and concentration device: The bottom liquid of the cyclohexanol separation tower is subjected to membrane filtration and concentration treatment. The filtered clear liquid mainly containing cyclohexanol and cyclohexene enters the cyclohexanol refining tower, the hydrated catalyst is intercepted and concentrated, and the concentrated liquid enters the catalyst recovery device; Wherein, the catalyst filtration and concentration method of the membrane filtration and concentration device is dead-end filtration and / or cross-flow filtration, preferably, the filtration method is dead-end filtration; Wherein, the membrane filtration and concentration device comprises multiple groups of filtration devices connected in series and or in parallel; The filter element is provided in the filtering device, and the filter element is made of one or more of metal, ceramic, titanium oxide, and silicon dioxide. Preferably, the filter element is made of one or more of metal, titanium oxide, and silicon dioxide. The filter element structure is a single-layer or multi-layer composite structure, and preferably, the filter element structure is a multi-layer composite structure; The filter element has a filtration surface accuracy of 0.05 to 1.5 μm, preferably 0.05 to 1 μm; the membrane filtration and concentration device includes a backwash system; The backwash medium is one or more of the following: the recovered reaction liquid, the filtered clear liquid, the refined cyclohexanol, and the cyclohexene hydration reaction raw material liquid. Preferably, the backwash medium is the recovered reaction liquid and / or the filtered clear liquid. The backwash pressure difference is 0.5-6.0 bar, preferably, the backwash pressure difference is 2-4 bar; Among them, the recoil mode is pressure driven or pump driven; Among them, the object of a single backwash is a single or multiple filter devices; The online backwashing time interval of a single filter is 5 to 360 minutes, preferably 10 to 90 minutes. The single backwash time is 0.5 to 30 seconds, preferably 1 to 8 seconds. Catalyst recovery device: recovers the catalyst and reaction liquid from the hydrated catalyst concentrate; The recovered catalyst may be returned to the reaction system, and the amount returned to the reaction system is 0-100% of the total amount of the recovered catalyst. Preferably, the recovered catalyst is not returned to the reaction system; Cyclohexanol refining tower: purifies the filtered clear liquid from the membrane filtration and concentration device to obtain refined cyclohexanol.

[0007] Beneficial effects of the present invention: 1) The catalyst filtration and concentration position is set after the cyclohexanol separation, which results in a small processing capacity of the filtration device, small equipment volume, low investment and low operating cost; 2) The catalyst in the hydration reaction liquid is intercepted by filtration, which is simple to operate and has a good interception effect; 3). The backflush system helps to ensure the filtration efficiency of the filter element and achieve long-term stable operation; BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic diagram of the process flow of the present invention. Specific embodiments

[0008] The following examples are used to illustrate the present invention. It should be emphasized that these examples are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Example

[0009] Cyclohexanol separation tower: The reaction liquid containing the hydration catalyst is distilled, and the light components are discharged from the top of the distillation tower, and the bottom liquid containing the catalyst enters the membrane filtration concentration device; Membrane filtration and concentration device: The bottom liquid of the cyclohexanol separation tower is subjected to membrane filtration and concentration treatment. The filtered clear liquid containing cyclohexanol and cyclohexene enters the cyclohexanol refining tower, the hydrated catalyst is intercepted and concentrated, and the concentrated liquid enters the catalyst recovery device; Catalyst recovery device: recovers the catalyst and reaction liquid from the hydrated catalyst concentrate; Cyclohexanol refining tower: purifies the filtered clear liquid from the membrane filtration and concentration device to obtain refined cyclohexanol.

[0010] The membrane filtration and concentration device includes two parallel dead-end filters. The filter element inside the filter is a multi-layer composite structure, made of 316L material, with a filter surface accuracy of 0.5 μm. The filtration temperature is 75 °C, the filtration pressure difference is 23 KPa, the backwash medium is the filtered clear liquid, the backwash pressure difference is 3.0 bar, and the backwash method is pump-driven. The single backwash object is a single filter device. The online backwash time interval of a single filter is 15 minutes, and the single backwash time is 3 seconds. The recovered catalyst is not returned to the reaction system. After testing, the filtration flux of the filter element is 0.71 m 3 / (h∙m 2 ); After testing, the turbidity of the filtered clear liquid was determined to be 0.12 NTU, indicating that the filter had a significant interception effect on the catalyst.

[0011] Example 2: Cyclohexanol separation tower: The reaction liquid containing the hydrated catalyst is subjected to distillation treatment, the light components are discharged from the top of the distillation tower, and the bottom liquid containing the catalyst enters the membrane filtration concentration device; Membrane filtration and concentration device: The bottom liquid of the cyclohexanol separation tower is subjected to membrane filtration and concentration treatment. The filtered clear liquid containing cyclohexanol and cyclohexene enters the cyclohexanol refining tower, the hydrated catalyst is intercepted and concentrated, and the concentrated liquid enters the catalyst recovery device; Catalyst recovery device: recovers the catalyst and reaction liquid from the hydrated catalyst concentrate; Cyclohexanol refining tower: purifies the filtered clear liquid from the membrane filtration and concentration device to obtain refined cyclohexanol.

[0012] The membrane filtration and concentration device includes two parallel dead-end filters. The filter element inside the filter is a multi-layer composite structure, made of 316L material, with a filter surface accuracy of 0.3 μm. The filtration temperature is 75 °C, the filtration pressure difference is 30 KPa, the backwash medium is the filtered clear liquid, the backwash pressure difference is 3.0 bar, and the backwash method is pump-driven. The single backwash object is a single filter device. The online backwash time interval of a single filter is 15 minutes, and the single backwash time is 3 seconds. The recovered catalyst is not returned to the reaction system. After testing, the filtration flux of the filter element is 0.58 m 3 / (h∙m 2 ); After testing, the turbidity of the filtered clear liquid was determined to be 0.11 NTU, indicating that the filter had a significant interception effect on the catalyst. Example

[0013] Cyclohexanol separation tower: The reaction liquid containing the hydration catalyst is distilled, and the light components are discharged from the top of the distillation tower, and the bottom liquid containing the catalyst enters the membrane filtration concentration device; Membrane filtration and concentration device: The bottom liquid of the cyclohexanol separation tower is subjected to membrane filtration and concentration treatment. The filtered clear liquid containing cyclohexanol and cyclohexene enters the cyclohexanol refining tower, the hydrated catalyst is intercepted and concentrated, and the concentrated liquid enters the catalyst recovery device; Catalyst recovery device: recovers the catalyst and reaction liquid from the hydrated catalyst concentrate; Cyclohexanol refining tower: purifies the filtered clear liquid from the membrane filtration and concentration device to obtain refined cyclohexanol.

[0014] The membrane filtration and concentration device includes two parallel dead-end filters. The filter element inside the filter is a multi-layer composite structure, made of 316L material, with a filter surface accuracy of 0.5 μm. The filtration temperature is 75 °C, the filtration pressure difference is 35 KPa, the backwash medium is the filtered clear liquid, the backwash pressure difference is 1.5 bar, and the backwash method is pump-driven. The single backwash object is a single filter device. The online backwash time interval of a single filter is 15 minutes, and the single backwash time is 3 seconds. The recovered catalyst is not returned to the reaction system. After testing, the filtration flux of the filter element is 0.60 m3 / (h∙m 2 ); After testing, the turbidity of the filtered clear liquid was determined to be 0.08 NTU, indicating that the filter had a significant interception effect on the catalyst.

Claims

1. A cyclohexene hydration catalyst filtration recovery process, characterized in that: include: Cyclohexanol separation tower: The reaction liquid containing the hydration catalyst is distilled, and the light components are discharged from the top of the distillation tower, and the bottom liquid containing the catalyst enters the membrane filtration concentration device; Membrane filtration and concentration device: The bottom liquid of the cyclohexanol separation tower is subjected to membrane filtration and concentration treatment. The filtered clear liquid containing cyclohexanol and cyclohexene enters the cyclohexanol refining tower, the hydrated catalyst is intercepted and concentrated, and the concentrated liquid enters the catalyst recovery device; Catalyst recovery device: recovers the catalyst and reaction liquid from the hydrated catalyst concentrate; Cyclohexanol refining tower: purifies the filtered clear liquid from the membrane filtration and concentration device to obtain refined cyclohexanol.

2. The process according to claim 1, characterized in that The catalyst filtration and concentration method of the membrane filtration and concentration device is dead-end filtration and / or cross-flow filtration.

3. The process according to claim 1 or 2, characterized in that: The membrane filtration and concentration device includes multiple groups of filtering devices connected in series and or in parallel. The filtering devices are equipped with filter elements. The filter elements are made of one or more of metal, ceramic, titanium oxide, and silicon dioxide. The filter element structure is a single-layer or multi-layer composite structure.

4. The process according to claim 1 or 2, characterized in that: The filter surface accuracy of the filter element is 0.05~1.5 μm.

5. The process according to claim 1 or 2, characterized in that: The membrane filtration concentration device includes a backwash system. The backwash medium is one or more of the recovered reaction liquid, filtered clear liquid, refined cyclohexanol, and cyclohexene hydration reaction raw material liquid. The backwash pressure difference is 0.5~6.0 bar. The backwash method is pressure-driven or pump-driven. The object of a single backwash is a single or multiple filter equipment. The backwash time interval of a single filter equipment is 5~360 minutes, and the single backwash time is 0.5~30 seconds.

6. The process according to claim 1, characterized in that The recovered catalyst can be returned to the reaction system, and the amount returned to the reaction system is 0-100% of the total amount of the recovered catalyst.

7. The process according to claim 1, characterized in that The membrane filtration concentration process is a continuous operation process, and the catalyst recovery device is operated in a continuous and or intermittent manner.

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